I would love it if armor like HellJumper or Hunter got unlocked from completing something in the campaign as a challenge set of armor, like how Recon was back in Halo 3.
Recruit - Bronze
Made your first hot drop into HaloWaypoint.com
View your Service Record on the web.
Become a member of an active Spartan Company.
Awarded to players of Halo: Fireteam Raven.