the composite artifact are only in the gift bag?

Yes. They are probably the biggest addition to KBAP yet.

I guess, though they aren't horribly useful. The gloves require you give up your OMG crown of chaos, and the ring of light takes your sandals away. I just don't think the items are worth losing some of your better items for.

Absolutely, but let's not forget that you can assemble and dismantle that artifact (it's gloves, but whatever) at will, so you practically lose nothing. Whenever you need the resistances, simply dismantle it :)

Hmm, I play very control oriented, and almost never rely on my spellbook for damage. Most of my games (even as a mage) have ~0% total damage from spellbook. So the Gloves seem like just me losing 5 mana and rage.