Melee Prowess: Drop sources, locations, and probabilities
Mobs Dropping Melee Prowess
Melee Prowess can be dropped by most ennemies in Warframe. You should probably consider this as your primary farm source.
Other items:
Melee Doughty - Melee Fortification - Melee Guidance
Melee Riven Mod - Melee Vortex - Melee Afflictions
Melee Doughty - Melee Fortification - Melee Guidance
Melee Riven Mod - Melee Vortex - Melee Afflictions