Rank 7 weapons can only be obtained by playing on Extreme difficulty. Information originally comes from a Japanese source here.[hinthint.hatenadiary.com] Weapon power will vary. Some weapons are likely missing, if you know any let me know and I'll check their location and see if I can get it, then add it in.

Longstroke 2++
Damage type: Physical
Power: 550
Effective Range: 20
Rate of fire: 163
Accuracy score: B+
Ammo Capacity/Fire type: 11/Semi-auto
Stat reqs: 52 str/36 dex/305 weight
DPS (single/dual): 1494/2988
Drop location and enemy type: SBC Fluegel Depths and Stern from Light Facsimile

Doverie++
Damage type: Physical
Power: 490
Effective Range: 15
Rate of fire: 200
Accuracy score: A
Ammo Capacity/Fire type: 9/Semi-auto
Stat reqs: 48 str/34 dex/301 weight
DPS (single/dual): 1633/3267
Drop location and enemy type: Ship Graveyard from Heartless Puppet

Betelgeuse 2++
Damage type: Optical
Power: 556
Effective Range: 30
Rate of fire: 180
Accuracy score: A
Ammo Capacity/Fire type: 15/Semi-auto
Stat reqs: 36 str/26 dex/196 weight
DPS (single/dual): 1668/3336
Drop location and enemy type: Forgotten woods/SBC Fluegel Stern from Handgun Drone and Enemy Caller

Paralytic Tusk +
Damage type: Physical
Power: 462
Effective Range: 15
Rate of fire: 200
Accuracy score: A
Ammo Capacity/Fire type: 16/Semi-auto
Stat reqs: 50 str/45 dex/306 weight
DPS (single/dual): 1540/3080
Drop location and enemy type: Final boss - Normal ending

HGBST3 Shigure
Damage type: Physical
Power: 374
Effective Range: 15
Rate of fire: 300
Accuracy score: B+
Ammo Capacity/Fire type: 21/Tri-burst
Stat reqs: 32 str/48 dex/257 weight
DPS (single/dual): 1870/3740
Drop location and enemy type: SBC Flugel Depths from Enemy Caller

SPB Night Sky MK3
Damage type: Physical
Power: 335
Effective Range: 20
Rate of fire: 200
Accuracy score: B+
Ammo Capacity/Fire type: 20/Semi-auto
Stat reqs: 16 str/30 dex/160 weight
DPS (single/dual): 1117/2233
Drop location and enemy type: Outskirts Facility, SBC Glocken Underground Ruins from Light Facsimile

Procyon SL3
Damage type: Optical
Power: 150
Effective Range: 25
Rate of fire: 761
Accuracy score: B+
Ammo Capacity/Fire type: 40/Full auto
Stat reqs: 12 str/40 dex/102 weight
DPS (single/dual): 1903/3805
Drop location and enemy type: Forgotten Woods, SBC Glocken Underground Ruins from Blocking Crystal

Valkyrie MK 2++
Damage type: Physical
Power: 330
Effective Range: 10.5
Rate of fire: 120
Accuracy score: E+
Ammo Capacity/Fire type: 7/Semi-auto
Stat reqs: 56 str/31 dex/565 weight
DPS (single/dual): 660/1320
Drop location and enemy type: SBC Flugel Bow and Abandoned Road from P Recon Automaton

Benenstock 87++
Damage type: Physical
Power: 519
Effective Range: 12.5
Rate of fire: 66
Accuracy score: E
Ammo Capacity/Fire type: 15/Semi-auto
Stat reqs: 27 str/50 dex/390 weight
DPS (single/dual): 571/1142
Drop location and enemy type: Subway B from Recon Automaton

Peacock 3
Damage type: Optical
Power: 235
Effective Range: 25
Rate of fire: 112
Accuracy score: E+
Ammo Capacity/Fire type: 20/Semi-auto
Stat reqs: 27 str/50 dex/390 weight
DPS (single/dual): 439/877
Drop location and enemy type: SBC Glocken Underground Ruins from Shotgun Drone

Draque L Shamal
Damage type: Physical
Power: 316
Effective Range: 20
Rate of fire: 448
Accuracy score: B
Ammo Capacity/Fire type: 64/Full auto
Stat reqs: 37 str/39 dex/515 weight
DPS (single/dual): 2359/4781
Drop location and enemy type: Outskirts Facility, and Forgotten Woods from P Barrage Automaton and Enemy Players. (Enemy Players in this instance seems to be any Enemy Player groups.)

Sirius 3
Damage type: Optical
Power: 223
Effective Range: 30
Rate of fire: 736
Accuracy score: B+
Ammo Capacity/Fire type: 80/Full auto
Stat reqs: 22 str/56 dex/525 weight
DPS (single/dual): 2735/5741
Drop location and enemy type: Forgotten Woods from Enemy Player

Sturm KZ MK3
Damage type: Physical
Power: 216
Effective Range: 20
Rate of fire: 634
Accuracy score: C+
Ammo Capacity/Fire type: 40/Full auto
Stat reqs: 16 str/44 dex/280 weight
DPS (single/dual): 2282/4565
Drop location and enemy type: SBC Glocken Underground Ruins from SMG Drone and Medium Facsimile

Spiral Shadow 2++
Damage type: Physical
Power: 270
Effective Range: 20
Rate of fire: 522
Accuracy score: B
Ammo Capacity/Fire type: 63/Full auto
Stat reqs: 45 str/33 dex/405 weight
DPS (single/dual): 2349/4698
Drop location and enemy type: SBC Glocken Underground Ruins from Recon Automaton

SPB Palladium++
Damage type: Physical
Power: 238
Effective Range: 25
Rate of fire: 669
Accuracy score: C+
Ammo Capacity/Fire type: 50/Full auto
Stat reqs: 27 str/40 dex/420 weight
DPS (single/dual): 2654/5307
Drop location and enemy type: Underground Labyrinth, Abandoned Road and Lighthouse from Barrage Automaton

Robust MK3
Damage type: Physical
Power: 325
Effective Range: 25
Rate of fire: 447
Accuracy score: B
Ammo Capacity/Fire type: 40/Full auto
Stat reqs: 69 str/22 dex/745 weight
DPS (single/dual): 2421/4842
Drop location and enemy type: SBC Glocken Underground Ruins from P Assault Automaton.

Lupus 3
Damage type: Optical
Power: 460
Effective Range: 35
Rate of fire: 317
Accuracy score: B+
Ammo Capacity/Fire type: 40/Tri-burst
Stat reqs: 29 str/62 dex/445 weight
DPS (single/dual): 2430/4860
Drop location and enemy type: Any enemy players.

Midou-Type AR Kou
Damage type: Physical
Power: 240
Effective Range: 27.5
Rate of fire: 596
Accuracy score: B
Ammo Capacity/Fire type: 50/Full auto
Stat reqs: 34 str/67 dex/514 weight
DPS (single/dual): 2384/4768
Drop location and enemy type: SBC Flugel Depths and SBC Flugel Stern from P Assault Automaton

LMG Pluie++
Damage type: Physical
Power: 225
Effective Range: 32.5
Rate of fire: 585
Accuracy score: C+
Ammo Capacity/Fire type: 200/Full auto
Stat reqs: 61 str/29 dex/925 weight
DPS (single/dual): 2193/4387
Drop location and enemy type: Subway B from P Assault Automaton

LMG Kumtag+
Damage type: Physical
Power: 271
Effective Range: 35
Rate of fire: 514
Accuracy score: B+
Ammo Capacity/Fire type: 150/Full auto
Stat reqs: 58 str/52 dex/935 weight
DPS (single/dual): 2321/4643
Drop location and enemy type: Forgotten Woods and Abandoned Road from P Assault Automaton

MG Mutnovsky++
Damage type: Physical
Power: 288
Effective Range: 37.5
Rate of fire: 480
Accuracy score: B
Ammo Capacity/Fire type: 100/Full auto
Stat reqs: 54 str/67 dex/960 weight
DPS (single/dual): 2304/4608
Drop location and enemy type: Old South from Mjonir

Alfubel+
Damage type: Physical
Power: 170
Effective Range: 32.5
Rate of fire: 818
Accuracy score: A
Ammo Capacity/Fire type: 60/Full auto
Stat reqs: 51 str/55 dex/635 weight
DPS (single/dual): 2317/4635
Drop location and enemy type: Forgotten Woods from Guide to the Abyss

SPB Rapier MK3
Damage type: Physical
Power: 211
Effective Range: 27.5
Rate of fire: 596
Accuracy score: A
Ammo Capacity/Fire type: 50/Full auto
Stat reqs: 48 str/36 dex/579 weight
DPS (single/dual): 125.8/251.5
Drop location and enemy type: Old South from Beleaguring Apostle and Enemy Players

Sylph-type B++
Damage type: Physical
Power: 173
Effective Range: 30
Rate of fire: 818
Accuracy score: B
Ammo Capacity/Fire type: 60/Full auto
Stat reqs: 42 str/54 dex/565 weight
DPS (single/dual): 141.3/282.6
Drop location and enemy type: Old South from Solo Stinger

AMR Tiamat MK2+
Damage type: Physical
Power: 2351
Effective Range: 75
Rate of fire: 40
Accuracy score: A+
Ammo Capacity/Fire type: 7/Bolt-action
Stat reqs: 76 str/50 dex/1505 weight
DPS (single/dual): 1567/Can't dual-wield
Drop location and enemy type: Abandoned Road from Gospet

AMR Deathwind
Damage type: Physical
Power: 2535
Effective Range: 62.5
Rate of fire: 36
Accuracy score: A+
Ammo Capacity/Fire type: 5/Bolt-action
Stat reqs: 76 str/42 dex/880 weight
DPS (single/dual):1521/Can't dual-wield
Drop location and enemy type: Sea Watchtower from Concealed Gendu

Force
Damage type: Physical
Power: 1702
Effective Range: 55
Rate of fire: 52
Accuracy score: A
Ammo Capacity/Fire type: 10/Bolt-action
Stat reqs: 68 str/49 dex/810 weight
DPS (single/dual): 1475/Can't dual-wield
Drop location and enemy type: SBC Flugel Depths and SBC Glocken Underground Ruins from P Sniper Automaton

Al-Nassr 3
Damage type: Optical
Power: 756
Effective Range: 60
Rate of fire: 200
Accuracy score: A+
Ammo Capacity/Fire type: 20/Dual-burst
Stat reqs: 34 str/61 dex/530 weight
DPS (single/dual): 2520/Can't dual-wield
Drop location and enemy type: SBC Flugel Bow from Brionac

Serene++
Damage type: Physical
Power: 360
Effective Range: 40
Rate of fire: 590
Accuracy score: A
Ammo Capacity/Fire type: 20/Full auto
Stat reqs: 35 str/78 dex/476 weight
DPS (single/dual): 3540/Can't dual-wield
Drop location and enemy type: Old South from P Sniper Automaton

Dragonbreaker++
Damage type: Physical
Power: 1076
Effective Range: 45
Rate of fire: 138
Accuracy score: A
Ammo Capacity/Fire type: 10/Semi-auto
Stat reqs: 46 str/51 dex/611 weight
DPS (single/dual): 2475/Can't dual-wield
Drop location and enemy type: Underground Labyrinth from Sniper Automaton

MEBR Maniac++
Damage type: Physical
Power: 674
Effective Range: 50
Rate of fire: 150
Accuracy score: A
Ammo Capacity/Fire type: 28/Semi-auto
Stat reqs: 41 str/76 dex/670 weight
DPS (single/dual): 1685/Can't dual-wield
Drop location and enemy type: Abandoned Road from P Sniper Automaton

Big Bear MK3
Damage type: Physical
Power: 380
Effective Range: 40
Rate of fire: 750
Accuracy score: D
Ammo Capacity/Fire type: 9999/Full auto
Stat reqs: 98 str/57 dex/1060 weight
DPS (single/dual): 4750/Can't dual-wield
Drop location and enemy type: SBC Flugel Depths from Breaker Facsimile

Gaint++
Damage type: Physical
Power: 380
Effective Range: 45
Rate of fire: 900
Accuracy score: D+
Ammo Capacity/Fire type: 9999/Full auto
Stat reqs: 117 str/69 dex/1550 weight
DPS (single/dual): 5700/Can't dual-wield
Drop location and enemy type: Old South from Hidden Seeker

Devil's Roar+
Damage type: Physical
Power: 366
Effective Range: 50
Rate of fire: 1050
Accuracy score: D+
Ammo Capacity/Fire type: 9999/Full auto
Stat reqs: 141 str/36 dex/1999 weight
DPS (single/dual): 6405/Can't dual-wield
Drop location and enemy type: SBC Flugel Depths and Abandoned Road from Enemy Caller and Ruins Gate

Benetnasch 3
Damage type: Optical
Power: 261
Effective Range: 60
Rate of fire: 1200
Accuracy score: C
Ammo Capacity/Fire type: 9999/Full auto
Stat reqs: 48 str/76 dex/795 weight
DPS (single/dual): 5220/Can't dual-wield
Drop location and enemy type: Forgotten Woods from Photonic Smog

GL6 Disaster+
Damage type: Explosive
Power: 1967
Effective Range: 15
Rate of fire: 52
Accuracy score: C
Ammo Capacity/Fire type: 6/Semi-auto
Stat reqs: 44 str/41 dex/605 weight
DPS (single/dual): 1705/3410
Drop location and enemy type: Forgotten Woods and Forest Edge from Gatekeeper and Nephilim Replica

GL6 Inferno ++
Damage type: Explosive
Power: 2039
Effective Range: 15
Rate of fire: 52
Accuracy score: C
Ammo Capacity/Fire type: 6/Semi-auto
Stat reqs: 61 str/33 dex/695 weight
DPS (single/dual): 1767/3534
Drop location and enemy type: Worm Nest from Overgrown Serpent

Explosion ++
Damage type: Physical / Explosive
Power: 1250 / 2916
Effective Range: 15
Rate of fire: 75
Accuracy score: C
Ammo Capacity/Fire type: 1/Semi-auto
Stat reqs: 78 str/35 dex/1000 weight
DPS (single/dual): 5207/Can't dual-wield
Drop location and enemy type: SBC Flugel Depths from Destroyer Facsimile

Spicule
Damage type: Physical / Explosive
Power: 570 / 1710
Effective Range: 12.5
Rate of fire: 75
Accuracy score: C
Ammo Capacity/Fire type: 2/Semi-auto
Stat reqs: 64 str/45 dex/830 weight
DPS (single/dual): 2850/Can't dual-wield
Drop location and enemy type: SB C Flugel Depths from Wary Heirophant

Deneb Kaitos 2++
Damage type: Optical / Explosive
Power: 667 / 1338
Effective Range: 12.5
Rate of fire: 75
Accuracy score: C
Ammo Capacity/Fire type: 3/Semi-auto
Stat reqs: 32 str/69 dex/623 weight
DPS (single/dual): 2506/Can't dual-wield
Drop location and enemy type: SBC Flugel Depths from Launcher Drone

Dainsleif
Damage type: Melee
Power: 717
Stat reqs: 44 str/45 dex/405 weight
Drop location and enemy type: Final Boss - True end

Masamune G2
Damage type: Melee
Power: 722
Stat reqs: 40 str/24 dex/320 weight
Drop location and enemy type: SBC Glocken Underground Ruins from Engineer Facsimile

Masamune G4
Damage type: Melee
Power: 719
Stat reqs: 40 str/24 dex/320 weight
Drop location and enemy type: SBC Glocken Underground Ruins from Engineer Facsimile

Kikuichimonji F2++
Damage type: Melee
Power: 624
Stat reqs: 32 str/57 dex/325 weight
Drop location and enemy type: Outskirts Facility from Quick Facsimile

Kikuichimonji F4++
Damage type: Melee
Power: 586
Stat reqs: 32 str/57 dex/325 weight
Drop location and enemy type: SBC Flugel Depths from Medium Facsimile

Kikuichimonji F9++
Damage type: Melee
Power: 592
Stat reqs: 32 str/57 dex/325 weight
Drop location and enemy type: Forgotten Woods from Heavy Facsimile

Apr 22, 2018 5:18 PM EST - Fixed some gun names and some placeholder dps numbers I had missed based on comments.
Mar 16, 2018 8:24 EST - Fixed some locations and the description on Deneb Kaitos based on comments.
Mar 5, 2018 6:45 EST - Fixed name on "Apache" to Beleaguring Apostle.
Mar 3, 2018 8:20 EST - Fixed some more bad translations on enemy names, still need to figure out what the enemy "Apache" is referring to, I'm assuming one of the flying mobs.
Mar 3, 2018 8:04 EST - Removed the random filler numbers in DPS and updated them to a basic formula. Weapon Power x Rate of Fire (RPM) / 60 seconds.
Mar 3, 2018 6:32 EST - Added some more drop locations to some weapons.
Mar 2, 2018 7:03 EST - Added SPB Palladium to SMGs.
Mar 2, 2018 5:20 EST - Added Sylph-Type B+ to Assault Rifles. Cleaned up some bad translations.