This is excellent, and I think it may be the first gauntlet-based class I've ever seen. It's also, as Dralnu said, quite balance; I'd put it somewhere around the Warlock or a Swordsage. The spell list looks solid and the class features synergize well.
However, I think you should clarify this:
Possibly include some sort of "must be his -4 his CR or up" and "must be hostile to him" statements?The Disciple's foe must pose a legitimate threat for him to benefit from Martial Metamagic.