You use your gauntlet to shield you from harm.
Benefit(s): When using this style, if you begin your turn wearing a gauntlet or spiked gauntlet on your off hand, and you are not using that hand to hold or make attacks with any other weapons or shield, you gain a +1 shield bonus to AC. You lose this shield bonus whenever you attack with your gauntlet or hold a weapon or shield in that hand. While receiving this shield bonus to AC, your gauntlet or spiked gauntlet is treated as a buckler for the purpose of using other feats and abilities (though you are also considered to have a free hand). This feat acts as the Improved Unarmed Strike feat for the purpose of satisfying the prerequisites of the Deflect Arrows and Snatch Arrows feats.
Pathfinder Player Companion: Armor Master’s Handbook © 2016, Paizo Inc.; Authors: Alexander Augunas, Robert Brookes, Anthony Li, Luis Loza, and David Schwartz.