Also longrifles already exist. They were the example for Revisions.
You're wrong here (thank heaven, long rifles were actually in an earlier tech revision that never got posted, so you had me scared), Long Rifles are present in the books, but not as a starting tech in this game.
The revision example was how you
couldn't use a revision to get a rifle out of a cannon.
Also (this one I'm unsure) but webbing specifically energised by a core crystal seems to be what charges a core crystal. Little pre-charged ones are strapped in a gaintlet (I think)
I'm not sure if you could energise a tunic (I don't see why not) but then an aethercannon shot hitting it would cause unoleaseant results.
So, this question is actually not clarified in the books, and I feel it needs to be. A small amount of the explanation will breach Jim Butcher's cannon, but, well, he never explains how exactly the mechanics of aetheric weapons work. Because that would be a waste of space in a story that
isn't fundamentally about naval warfare.
So, gauntlets, comprised of three major parts, the cage, the power system, and the actual emitter.
The cage is primarily made from copper, it wraps across the wrist and forearm and provides structure. Copper links join the hand and forearm pieces in order to allow mobility.
The power system is mounted into the forearm, and is basically a couple inches of aethersilk and a core crystal the size of your thumb hidden under an armored clasp to prevent jarring.
The emitter is a slightly canted piece of bronze and copper mounted into the palm, the angling allowing a soldier to fire straight without actually needing to bend his wrist 90 degrees upward. The weapons crystal fitted within is tiny, but effective at fort short range anti-infantry use.