Today I was discussing some of the rings with a warrior, and he was showing me that he has an archon ring that boosts his armor by 5%. Yet the stats on the ring says 2.5%. But clearly it was 5%, we did the calculations.

All the archon rings give an extra passive bonus, and all the bonuses are 2.5%. Some give armor, some give crit, and some give damage. I'm not sure if the crit & damage bonus rings have the same error, but it appears at least one of the armor bonus rings has this bug.

The ring in question was the "of grace" version for warrior. I forget the exact stats.

So there is either an error in the stats listed, or in the ring applying the stats. Either the stats should say 5%, or the ring should only give 2.5%.