Another weapon revealed in the Multiplayer video release was a covenant automatic weapon, apparently a successor to the plasma rifle and repeater. It acts similar to it's predecessors in that it overheats quickly if used on full auto. However check out this video for the Spartan Ops game modes and in game multiplayer action. Assassinations are still in too, check out the one on the AI Knight (cant remember full name) in spartan ops.
Enjoy!