Its his "Energy Fist" Where he stores all his magic spells and increases his strength! (total guess, hope I win!)
It is a magic gauntlet. The gauntlet can be charged. When charged, Zack is able to release unique (special) attacks.
Large Energy Gauntlet that allows the character to wield heavy weaponry or posess extraodinary skills. I followed and retweeted on twitter @phoenix526 also This game looks like a high quality, polished and action packed RPG adventure like GameEvil's Zenonia. I look forward to reviewing this title!
It should be a gauntlet that allows you to collect energy to perform skills. The gauntlet also should have powers that include push or pull enemies away or closer to you. Basically, You use the gauntlet for gravitational forces plus to collect energy and perform skills. It could be a keepsake from a character from the game.(his father)
A HUUUGE ASS Gauntlet! Looks like a magical(or mechanical, as it looks to be powered by magnets/electrical current) gauntlet and *should* be used for magical(or energy based skills) and defensive purposes (because if he doesnt use it as that, well, he's just stupid) EDIT: According to the video, that Gauntlet belonged once to a really powerful warrior and out hero got it somehow (unless he is about to become that warrior, but that would mess up his clothes so I doubt it) EDIT #2: And if none of my answers work, com2us has some that I'll borrow here "Some answers ex. muscle, finger accessory, Caligo Chaser, etc."