"Two become One" ( Kingdom hearts would be mentioned sooner or later) ~We turned Oryxs sword in to a weapon of light. So what else can we do...~ banshee Unique perk "Dark Edge" when held out you super will be like the mission on the moon when you have to destroy crotas sword. A slam dunk if you may. But the shock wave would be bigger and more darker. It won't kill in one hit but it blinds the enemy and leaves them at low hp (if in crucible). Or one shots low tier minion of darkness. One other exotic could be a revolver that fires 3 shots at once. But I have not fully fleshed out that idea so if you have any good statistics for it please reply.

The revolver with three shots should have decent range (for a hand cannon anyway) but much lower impact and a slightly larger magazine size (say 15-18 shots for 5-6 bursts) The actual perks could be something to refill the magazine after something happens or something else that's your call