The idea that a liar can be honorable is a stretch, in my mind. I'm curious though, as to seeing it in action. So I'll let that slide because hey, charmers gonna charm.
The key is in the details of the wording: he lies when he's just talking, but when he makes an actual promise, he keeps it.
He's also a bit young to know five kickass spells. I'd say knock it down to three, keep his signature one and probably two others but what he has so far is a bit much for a 25 year old chap who steals to get by (how much time can a thief have on his hands if he's always looking over his shoulder?).
Yeah, I misunderstood the premise. I thought the magic came from the shards, so people with no shards had no magic, and the power of your magic was more dependent on your shards than on your training/experience.
I'll fix that up shortly.
[edit]Done![/edit]