Anko on reflex had already pulled out a kunai and blocked each time the arm moved to strike cause she don't want to risk harming Sasuke with combat moves that are made to disarm a opponent. Seriously what person in there right mind would believe if Sasuke was harmed outside of combat practice saying his arm was moving on its own. That and Anko figures its the curse mark knowing it can do stuff like that which is another reason she wants to train him.''Sasuke why are you attacking so sloppy?'' by how she said that she didn't seem to found it strange Sasukes attacking her but in the back of her mind see thinks hes got no control over his arm at the moment by how he screamed