Cheers, and thanks for that!
I don't think we've ever explained our plans for enchants, but the short-short version is that they are various buffs to yourself or to NPCs, that make you improved in some way. It's more complex than that, but that's the gist.
For the crests, I think we've talked about them in at least the forums, but not sure about a diary. There's probably some details if you search. But the short-short version of those is that these are spellgem-holders that give buffs to the spellgem. However, that's just the most basic kind of crest, which holds only one gem. Better crests can hold a gem and some spellshaping gems to do compound effects. Things like adding homing, splitting a spell into multiple shots instead of one, or even adding a charge ability so that you can hold the button down to charge up power shots. All of that stuff with the crests is actually already implemented, but just not available because there are a number of glitches with it that we haven't had time to fix yet what with all the other stuff going on with the game. And we don't have a "socketing station" interface yet, which is needed for actually putting gems into the various slots in crests, etc.