in this topic there is ascreenshot of the ability: https://forums.obsidian.net/topic/101582-bug-passive-armor-blackened-plate/
As an additional note, I am also using the paladin aura "exalted endurance", which has this text:
Aura Range: 5m
Effects:
Self:
+1 Armor Rating, +3 Health Restored per 3.0 sec
Fills the paladin and his or her allies with unshakable confidence, increasing their Armor Rating.
Which I think explicits the misunderstanding, even if the tooltip says "self", it means that the aura is casted by self, but not actualy applied on self.