http://www.uesp.net/wiki/Skyrim:Arniel
Uh, I never had trouble talking to him. Try talking again. I don't recall there being any necros in the college to be honest.

While I'm somewhat like Serethil on knowing versus experiencing generally I'd like to be slightly surprised. Thanks, Bethesda. 
While I'm somewhat like Serethil on knowing versus experiencing generally I'd like to be slightly surprised. Thanks, Bethesda. 
), but, yeah, having to do that for bugs is bad. I like being surprised (ie I never looked up what Ebony, Daedric, and Dragon armor looked like before I made it), but I don't like playing partially through the game 10 times to get one 'clean' playthrough. 
I'm a pack rat so I don't sell unique stuff anyway, but I would've been pissed at myself had I sold a Dragon Priest mask before hearing about the 9th. 