Tonight me and some LS mates decided to rock old school SC-MB style party in the Mire. My cap with Z Mitts on Thundaga III MB was 3368. With the Sorc Gloves, it was 3418. This is roughly a 2% increase. So... MAB +7 for MB with these things. OFN yea, felt like posting though.
Hrm.. from all my tests (I have AFV2 Pants, Gloves, and Boots) the gloves add a variable 5-10% on the average magic burst..
Once however they added nearly 25% on a blizzaga III magicburst on a Darksteel golem. he resulting 1838 points of damage coupled with a ninja tank resulted in a surprised Tarutaru puddle.
If you are no longer getting resisted on your castsa, (which with the exception of weapons) these gloves or possible zenith gloves are the best equipment in the game for blms imho.
I have these, they are pretty dissapoiting. they only add 5%dmg to magic bursts, whereas zenith mitts add 5% damage to all nukes. mostly just a show item besides the dark skill
I have seen one 75BLM on sylph who had these and the Sabots. I tried to get a screeny, but he zoned out of Upper Jeuno before I could, and I had a PT in Gustav waiting for me.... /cry.