For those who will jump in when Update 13 hits the PS4 side, this is a tentative list of the type of weapon, the mod itself and which faction(s) will drop which mod. I will update the list when a final and definitive list is compiled. Sorry I do not have the exact location where these ne’er-do-wells and derelicts of alien society reside.

Melee Mods:

Katana – Tranquill Cleave – Frontier Butcher. Arid Butchers

Long Sword  – Iron Phoenix – Frontier Hellion Lancer, Frontier Heavy Gunner.  Crimson Dervish – Grineer Bombard

Dual Sword  – Crossing Snakes – Mine Osprey, Grineer.  Swirling Tiger – Anti Moa, Corpus Tech

Scythe – Reaping Spiral – Corpus Crewmen.  Stalking Fan – Sniper Crewman, Ruk

Fist (Brawlers) – Seismic Palm – Elite Lancers, Infested Leaper. Fracturing Wind – Crewman (Dera), Infested Charger

Hands & Feet – Grim Fury – Crewman (Detron), Powerfist.  Brutal tide – Corpus Tech, Toxic Ancient

Staff – Clashing Forest – Elite Crewmen (Flux). Flailing Branch – Corrupted Heavy

Glaive – Gleaming Talon – Shockwave Moa, Leech Osprey

Polearm – Shimmering Blight – Grineer Scorch, Grineer Seeker. Bleeding Willow – Corrupted Moa

Whip – Burning Wasp – Grineer Regulators, Corrupted Lancer.  Coiling Viper – Leech Osprey, Corrupted Crewman

Dagger – Homing Fang – Sniper Crewman.  Pointed Wind – Grineer Butcher, Guardsmen, Shockwave Moa

Dual Dagger – Gnashing Payara – Shockwave Moa, Elite Crewman.  Sinking Talon – Kela, Crewman (Detron)

Axe/Heavy Sword – Cleaving Whirlwind – Moa, Ancient Disrupter. Rending Crane – Grinner Flameblade

Hammer – Shattering Storm – Ballista, Ruk. Crushing Ruin – Jackal, Railgun Moa, Grineer Seeker

Machete – Sundering Weave – Scorpion, Grineer Scorchs, Eviscerator