I honestly think he’s just being figurative. “This is what I did for power. The magic of a genie was handed to you on a silver platter, but I gave my right hand for power. To wear the gauntlet is painful, but it’s worth it – worth it to destroy the likes of you.” (It is really, really sad the things I can quote by memory word for word.)
Like I said in that commentary, it’s vague enough that it could really go both ways, but I’m sticking to my guns on that. I think Mozenrath is talking fancy without being completely straightforward because this is still a pissing contest and he refuses to lose his composure (for the moment) when his injury’s just been laid completely bare. (This will completely fail when the sprites reveal they buried his gauntlet.)
Technically if he kept his hand in that thing’s mouth long enough to save the gauntlet, then he still totally did it for power. Let’s be real. I think his injury would have spread, and we’d see evidence, by his final episode, where he confirms that the gauntlet is weakening/killing him. It seems like it’s more a life force thing.
Unless I somehow manage to get an interview with one or two writers to confirm some of this, I can really only speculate. Either way, I think given how his right hand looks under the gauntlet, and they were able to get away with that at all, it’s possible they weren’t allowed to be explicit on how it got that way.
The DVD Fairy 