I do enjoy the shadow magic stuff from ToM, though.

They're 3rd edition, but I suggest looking at the Encyclopaedia Arcane. Star Magic is particularly interesting.
I knew I was forgetting something. Shadowcasters can play too, if they're nice, and don't go into the whole "plane of shadow" thing. If they can refluff themselves as fey-based or mist-based, then wonderful. I'm not familiar with the Encyclopaedia Arcane, but I'll look it up. is it 3rd party? Also, I do think the idea about the gnomes being tied to Allomancy is worth considering. They live in a region fairly high in metals, although I was hoping to make them somewhat animistic/shamanistic. Oh well. We have Urgals for that.

I landed on Kellus's fix for truenamers, which I rather like.

I think that's all for now. I'll get some non-DnD stuff done, then get the last vestiges up. The end is in sight...