Melee trading happens pretty frequently in Halo because of how often people finish gunfights with melee attacks. Instead of seeing two death messages in the kill feed where player A punches player B and vice versa, I suggest both messages would display a fistbump icon. The game could recognize when to do this by taking note of when two players kill each other with melee attacks in less than a second.
I find this idea dumb, and I love it.
Actually pretty smart, 343 do this please