Fable III

You must first get far enough on "The Road to Rule" to be able to buy this from a chest (it unlocks at the end of the cave where you fight hobbes for the first time). It costs 50 guild points to get. Now in order to get the achievement, go to the sanctuary and equip a different gauntlet on each hand. Cast the spell with B and the achievement will unlock. Cheers!

Not sure if this was a one-time glitch or not, but if someone could confirm that would be great.
I was in the middle of charging up a cast of just ice (didnt have the ability to use 2 gauntlets yet) and I was at lvl 3 charge when I suddenly got a popup with someone asking to join my game. I hit B to decline and immediately hit B again to charge again, and the achievement popped. Somehow it seemed to think that both charges were together in one cast.
Like I said, needs to be tested more. Not like it's hard to get the dual gauntlets anyway, but this would be for people that just want to get it done with.