This entire thread is predicated on the notion that the armor is indeed the exact same suit worn by all the arbiters. While I will admit that Halo makes it seem as though it MIGHT be the same suit, it could also be the same in that it is just a duplication of the suits of other arbiters. When I was in the Army, I would often hear refrences to "wearing the same uniform" of my peers and predicessors but they obviously weren't being literal.
The truly literal interpretation seems difficult at best to accept. Since the arbiters all seem to die violently it would stand to reason that their armor is not indestructable or the life expectancy of the arbiter wouldn't be so brutally short. Yet, in order to have the same suit passed on from one arbiter to the next would require the suit be litterally indestructable or else, through the course of damage done and the ensuing repairs it would rapidly cease to be the "same" and would be regularly replaced, at least in pieces.
So, in short you have two possible options. Either they are saying it's the same suit as a metaphor, or the suit is indestructable and just doesn't do a very good job of protecting the wearer. Either way there is no continuity error.