Mods are items that can "Modify" the attributes of weapons to a surprising degree. Weapon Accuracy and Damage output are obvious, but character HP/MP regeneration and Lucky as well with certain mods. Not all weapons can be modded as a Mod Slot is needed. Mods come in five different variants:
Fuel Tanks offer bonuses to streaming weapons primarily.
Tech Mods don't offer >>unverified<< damage bonuses >>unverified<<, but they do offer bonuses to how a weapon is used. Weapon Accuracy, Firing Accuracy, Range, Critical Rate, Critical Damage Bonus, and...