Instead of a new rarity, how about if we add like a custom part that would add a specific statistics to an existing item.
Adds an extra 1 use to these weapons: Nightfall, Annihilation, Spartan Carnage, Sweetie, Bloodweep. etc
Increases damage and improves range of: Last Words, Grim Cobra, Terror Cry, Night Eagle.
Increases damage of: Spinefall, Mighty Cannon, Desert Snake.
High-Capacity Battery Bank.
Increases FaceShocker’s or HeatPoint’s uses to 4 instead of 3.
Adds an extra 1 use of: Supreme Cannon, Abomination, Burning Shower, Red Rain.
Increases damage of beam based weapons.
Improves firing accuracy. (You will always get higher damage roll. Frantic Brute users rejoice.)
Depleted Uranium Shell. (very rare)
Doubles the damage of Falcon, Lightning Scope, and Flaming Scope.
Automatically activates drone at the beginning of the battle, without consuming your AP. (Doesn’t work on FaceShocker or HeatPoint.)