As in title this works only on offline servers, you can put any knife in the vanilla using commands.
If the tutorial helps you, I'll be happy to like, share, add to favorites, or send an award.
ATENTION: You need to execute the commands below this!
sv_cheats 1
mp_drop_knife_enable 1

Give Commands:

Classic knife:
give weapon_knife_css;ent_fire weapon_knife addoutput "classname weapon_knifegg"
M9 bayonet:
give weapon_knife_m9_bayonet;ent_fire weapon_knife addoutput "classname weapon_knifegg"
Butterfly knife:
give weapon_knife_butterfly;ent_fire weapon_knife addoutput "classname weapon_knifegg"
Karambit:
give weapon_knife_karambit;ent_fire weapon_knife addoutput "classname weapon_knifegg"
Bayonet
give weapon_bayonet;ent_fire weapon_knife addoutput "classname weapon_knifegg"
Gut Knife:
give weapon_knife_gut;ent_fire weapon_knife addoutput "classname weapon_knifegg"
Shadow Daggers:
give weapon_knife_push;ent_fire weapon_knife addoutput "classname weapon_knifegg"¨
Talon knife:
give weapon_knife_widowmaker;ent_fire weapon_knife addoutput "classname weapon_knifegg"
Falchion knife:
give weapon_knife_falchion;ent_fire weapon_knife addoutput "classname weapon_knifegg"
Stiletto knife:
give weapon_knife_stiletto;ent_fire weapon_knife addoutput "classname weapon_knifegg"
Huntsman Knife:
give weapon_knife_tactical;ent_fire weapon_knife addoutput "classname weapon_knifegg"
Survival Knife:
give weapon_knife_canis;ent_fire weapon_knife addoutput "classname weapon_knifegg"
Navaja Knife:
give weapon_knife_gypsy_jackknife;ent_fire weapon_knife addoutput "classname weapon_knifegg"
Nomad Knife:
give weapon_knife_outdoor;ent_fire weapon_knife addoutput "classname weapon_knifegg"
Ursus Knife:
give weapon_knife_ursus;ent_fire weapon_knife addoutput "classname weapon_knifegg"
Paracord Knife:
give weapon_knife_cord;ent_fire weapon_knife addoutput "classname weapon_knifegg"
Skeleton Knife:
give weapon_knife_skeleton;ent_fire weapon_knife addoutput "classname weapon_knifegg"
Bowie Knife:
give weapon_knife_survival_bowie;ent_fire weapon_knife addoutput "classname weapon_knifegg"
Flip Knife:
give weapon_knife_flip;ent_fire weapon_knife addoutput "classname weapon_knifegg"

Enjoy!