For multiplayer it could be true skill.
For armor its unlocked by credits earned through spartan ops.
It honestly preffer this then any of the others we had so far.
I hate the credit system, what happens when you unlock everything? There’s not really a point to play the game. I probably won’t play Spartan Ops very much, too much to do in Multiplayer and in Campaign. But, if there’s achievements for Spartan Ops, I’ll play it sometime. I don’t really like your idea, but I could see it working for certain armors but not all. Maybe some extra armor attachments or something.
This is going to be the last time I post this, Halo Reach matched players on a true skill system, it just didn’t have a representative number next to your name. I think Halo 4 will probably have a similar system as reach, credits for your rank but still matching players on a true skill system.