Well, seems like TSoG is starting to do what it's intened to do- raise some unpleasant questions, especially in the morality and ethics department.
It is a tad cruel, isn't it- taking someone's soul then reviving a teammate using it and, in the process, somehow discarding it. Does the soul feel uncomfortable? What happens to it? Or is it the life energy of a being, hence called soul charge, rather than the soul itself? How does Soul Suck work? Does it slowly, but surely nibble away at an enemy's soul, ripping it into little pieces, like humans eating a pie?
On topic though- I don't think Gelves would have the ability to construct such a complicated device- after all, they are not potent Gift users and, as im2msart4u put it, they feed off natural products, they don't feast on technology, and a soul capacitor does sound like a difficult device to make!
I agree with Barzul there as well- I think Craig should add in extra dialogue to allow players to release the soul charges, unless that's just energy stored from ripping a soul out of the body it occupies (bit like fission- energy is released when an atom is split up). Methinks it would be a good idea to ask Craig to define what a soul charge is, as it will have direct implications on the ethics of what Luca does.