Well, with 8 books to go or whatever there's plenty of time for him to make the slow descent in to real evil with some corrupting influence.
Before his inevitable last second change of character
And Ididgive a little internal 'Fuck yeah!' when he murdered that asshole.
Probably more like Chaotic Neutral, or whatever the nerds call it. He won't be dark like a bad guy, but I could see his judgement being clouded and doing bad things for good reasons.
Oh, and not really a nitpick, but that sword they gave to Szeth at the end seemed like a fairly blatant homage to Stormbringer, but when it said something along the lines of, "Hi there! Would you like to slay some evil today?" I cracked up. I can't imagine it is actually a "good" sword, but if it pretends to be, and continues to act like the paperclip from Microsoft Office, I'll probably love it anyway.
Did you read Warbreaker? Not that I can comment on Stormbringer or Moorcock, but maybe that is where he got the inspiration from. But the sword is a 'character' from that novel.