Illidan would be able to see an artifact if it was somehow magic, and he'd likely be very curious about it too! His vision isn't limited to people but anything in the environment really, provided there's some sort of magic and/or life to it.

So. Sanzo is going to be some obnoxious shit that just gives him an occasional migraine out of nowhere because he occasionally just bursts into holy magic. That's Rude Sanzo.