He's in the temple (Shade Lord dungeon) - you know the barrier that never opens, so you take the short cut around the lava pit instead? Well don't do that yet - walk up to the impenetrable barrier and he's right there.
I heard about the temple ruins foirst from this guy's brother, then later I visited immesvale. I still want the itthilium but i have not met his guy yet. So where is the guy?