The stats on that robe seem oddly similar to the Neriak Ceremonial Robe that drops in Hate. Unwearable, lore, magic, no drop. Maybe some sort of quest combining both robes together or something? Caster quest obviously, however, if this fellow is on Heretic faction, presumably not necromancer quest, since I believe, even if dark elf and gnome necromancers start out KOS to Paineel/Heretic faction, I believe that Erudites are not KOS to Neriak or Steamfont. (guessing on the Steamfont, verified the Neriak.) Ergo, chances are, they aren't asked to kill anything on Heretic faction for racial quests. The reverse is true, don't think any Paineel quests run around killing ANY evil characters, irrespective of KOS status.
Hate faction is essentially meaningless, as far as I can tell. I mean, I don't think it would truly nix your Neriak factions. However ... considering the death of an undead Erudite (probably from Paineel) and a second floor Hate drop, perhaps a lighty-based item? /ponder.
I love these little mysteries, I swear :)
Saminga Daemonregina, 56th Defiler of Rodcet Nife.