User blog comment:ClariS/Why Xerath's Passive is Bad/@comment-9713132-20130318110601/@comment-9713132-20130319102004

But that's what I mean. Xerath's armor passive is his form of extra durability buff during these early-game, lane trade fights. In comparison to Diana, she has a damage-soaking shield, so she can afford to continue autoattacking. Xerath's armor addition is IMO there to help his early-game lane trades.