Arbitor they outnumber us three to one!
Then it is an even fight.
Arbitor > Arbiter.
Arbitor = Rank above Arbiter.
A big thanks to kids that did this to 343 after they heard they get an infection game mode in halo 4 with no thought of normal playlists.
Used to be you had to buy all base helmet's and you could get it, but that was almost 2 year's ago, now as mike said you need to be an inheritor.