Halo 4 should have duel wielding, because the mark 6 armor was updated with the capabilities to track
the status of 2 weapons at once. also need duel needlers.
I have a few ideas.
Some sort of Forerunner (or Precursor) plasma grenade type thing.
A Sniper, with 1 shot per clip, that launches a large crystal, like in Needler, that explodes.
Destructible environment.
Hopefully all of the new trilogy on 360