Armor has an AE Fear (MENTAL) that lasts for roughly 15 to 20 seconds. He is also immune to Fighter taunts, so rogues HAVE to tank him. Does memory wipe every 20 or 40 seconds and goes for healers. You will see when this happens by his emote, "Heal No More!".
He is not an overly powerful mob, but his abilities of stuns and stifles and mem-wipes make him harder than expected.
Good Luck!