I think that your Armour and Helmet should get dented, and have visible evidence that it has been in battle, like chips in the paint, scorch marks, burns. rips, cracks in the visor, blood splatters and even deteroration like having pieces fall off, and by the end of the game your in game Spartan/ Elite is totally messed up, but it resets at the beggining of the next game.
Of course this isnt some flawless idea, the main issue is how they could do it with issues like lag and connection stuff, also the only way it would make sense realisticly is if your sheild was down during the event of it being damaged, but i think that the idea itself is good for replayablity and realism gameplay wise.