User blog comment:ClariS/Why Xerath's Passive is Bad/@comment-199.84.62.149-20130319160727/@comment-4881935-20130320032745

No they haven't. In fact, as the lore state, he joined the League to get rid of the armor he wears. So it implies that the armor is still weakening him.

the armor is actually useful. Even against a non-heavy AD team. Or, that's my opinion on it.