He's only been prodding at her invisible bubble with his feet thus far. He favors kicks because of old injuries to his arms (partially evidenced by the scars on them), and he's playing a simple bit of psychology. It's not the first time he's conditioned someone into thinking an attack will only come from his feet.

His right hand goes for a grab as he simultaneously sweeps his foot, hoping to upset her balance, throw her, and maybe get a bruise in while he's at it. He has no idea who he's dealing with.