Why create such a guide? Because the highest tier armor lacks any such bonus apart from the head piece. This information is publicly available, but I couldn't find it in a condensed easily accessible format and since it was useful to me I figure it might be useful to others as well.

Bitterblack Armor Level 3 is great for defense/utility, but not so much for offense. There is one exception to this tho, and that occurs on head pieces spawned with:

“Boosts Strength when you've been noticed by a large group of enemies”
Translates to: Increases Strength and Magick by certain amounts depending on the number of enemies http://dragonsdogma.wikia.com/wiki/Dark_Arisen_Bonus_Enhancements

• By 5% if 1 or 2 enemies
  
• By 10% if 3 or 4 enemies
  
• By 15% if 5 or 6 enemies
  
• By 20% if 7 or 8 enemies
  
• By 25% if 9 or more enemies

While the ingame description sounds... meh... The actual mechanic is quite impressive; even fighting just one enemy, the bonus will be far greater than any other head armor piece with a flat value on it, but I will still include them below.

For reference the above enhancement can appear on the following head pieces:
Nether Helm[dragonsdogma.wikia.com] / Hellfire Helm[dragonsdogma.wikia.com]
Hood of Shadow[dragonsdogma.wikia.com] / Hood of Oblivion[dragonsdogma.wikia.com]
Grave Veil[dragonsdogma.wikia.com] / Carrion Veil[dragonsdogma.wikia.com]

All of the above are possible purification results from a Bitterblack Armor Level 3 item

Also please note that all values below are BEFORE augments. So if you have Vehemence, Clout, Attunement, Acuity, Bloodlust, Autonomy, Opportunism, Exhilaration, Equanimity, or Eminence - the value you see in-game may be different.

The items below were pulled from this http://dragonsdogma.wikia.com/wiki/Category:Equipment_with_Bonus_Enhancements
Please let me know if I missed anything.

Magick
Diadem[dragonsdogma.wikia.com] +10
Laurel Circlet[dragonsdogma.wikia.com] +7
Circlet[dragonsdogma.wikia.com] +4

Strength / Magick
Dragonroar[dragonsdogma.wikia.com] +8/8
Dragon Band[dragonsdogma.wikia.com] +5/3
Chimeric Armet[dragonsdogma.wikia.com] +2/1

Strength
Barbarian Chief's Helm[dragonsdogma.wikia.com] +10
Meloirean Cyclops Veil[dragonsdogma.wikia.com] +8
Cyclops Veil[dragonsdogma.wikia.com] +6
Direwolf Veil[dragonsdogma.wikia.com] +5
Lupine Veil[dragonsdogma.wikia.com] +3

Magick
Trophy Jacket[dragonsdogma.wikia.com] +20

Strength / Magick
Berserkin[dragonsdogma.wikia.com] +3/10 (female only)
Chimeric Half Plate[dragonsdogma.wikia.com] +3/2

Strength
Golden Belt[dragonsdogma.wikia.com] +20
Swordsman's Plate[dragonsdogma.wikia.com] +5

Strength Clothing
Marshal's Bracers[dragonsdogma.wikia.com] +5
Chainmail Bracers[dragonsdogma.wikia.com] +3

Magick
Trophy Bracers[dragonsdogma.wikia.com] +20
Gleaming Bangles[dragonsdogma.wikia.com] +6
Alchemickal Bangles[dragonsdogma.wikia.com] +5
Jade Bangles[dragonsdogma.wikia.com] +4
Runic Bangles[dragonsdogma.wikia.com] +3
Tiger Bangle[dragonsdogma.wikia.com] +2
Bronze Bangles[dragonsdogma.wikia.com] +1

Strength / Magick
Chimeric Gauntlets[dragonsdogma.wikia.com] +2/1

Strength
Assailant's Bracers[dragonsdogma.wikia.com] +5
Swordsman's Bracers[dragonsdogma.wikia.com] +5
Champion's Bangles[dragonsdogma.wikia.com] +4
Bandit's Glove[dragonsdogma.wikia.com] +3

Magick
Trophy Boots[dragonsdogma.wikia.com] +30
Wizard's Boots[dragonsdogma.wikia.com] +4
Mage's Shoes[dragonsdogma.wikia.com] +3

Strength / Magick
Flame Skirt[dragonsdogma.wikia.com] +8/8 (female only)
Holy Cuisses[dragonsdogma.wikia.com] +7/7
Royal Cuisses[dragonsdogma.wikia.com] +5/5
Raptor Cuisses[dragonsdogma.wikia.com] +3/3
Chimeric Sabatons[dragonsdogma.wikia.com] +3/2

Strength
Assault Boots[dragonsdogma.wikia.com] +30
Striker's Greaves[dragonsdogma.wikia.com] +5
Swordsman's Greaves[dragonsdogma.wikia.com] +5

Strength / Magick Rings
Master Ring[dragonsdogma.wikia.com] +81/81 up to +100/100
Preceptor Ring[dragonsdogma.wikia.com] +51/51 up to +70/70
Baleful Nails[dragonsdogma.wikia.com] +10/10

Cloaks
Sovereign's Mantle[dragonsdogma.wikia.com] +10 str
Magnanimous Cloak[dragonsdogma.wikia.com] (no stats, but only other cloak with an enhancment on it)

If you have any constructive criticism or helpful comments - I welcome such feedback.
Or if you have any questions I'll do my best to help out.
Otherwise thank you for taking a look at my guide.
Remember to rate, like, and favorite this guide if you found it helpful :D

Also, please consider hiring my Pawn:

Morrigan
lvl 200 Utilitarian/ Medicant Mage (max height & 110 weight)
w/ Rusted Staff (for applying Torpor Debilitations)

High Comestion
Grand Levin
High Grapnel
Grand Anodyne
High Halidom
Holy Pact

http://gtm.steamproxy.vip/sharedfiles/filedetails/?id=885129615
http://gtm.steamproxy.vip/sharedfiles/filedetails/?id=885128941

She is my main account pawn so I have to constantly push that Medicant inclination back up to #2 but I try to make sure she is perfect again before each upload to the pawn server.

I'm still working on her bestiary 3 stars, so any help in that regard would be greatly appreciated. She is set to be available to everyone, but if you want to be sure to get her leave me a message here then friend me. I reject all friend requests unless you leave a message for me first.

If you found this guide useful you may also like my other guide:
http://gtm.steamproxy.vip/sharedfiles/filedetails/?id=895752139