Be creative here there are no wrong ideas.
I would like the Spartan laser to be a weapon personally, just called something different "Charge Rifle" was a name I had in mind
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An exotic Leg armor that can be equipped as a heavy weapon. Name it "The foot of Chuck Norris" (unlimited ammo) basically when you use it it looks like the Nuke going off in CallOfDuty. All enemies on the map die. Crota one hit kill.