A rail gun shotgun, with homing plasma lasers.
Each shot unloads some 30 lasers, and they began to home in on the nearest target, sticking to them and/exploding/hurting/tagging(for everyone to see, or for bots to go after) (one of those options)
Or, a knife that literally separates into segements, and you can throw each segment or use it as a whip to slice and dice your enemies. And/or it can be used to grapple.
Or-
wait.
I'm gonna loose all my ideas.
That's enough for now.