Her movement away from his palm strike is more downwards than it is sideways, meaning she took not even a half step to the side as she ducked under the strike. This would put his arm a few feet or inches above her left shoulder. Also, since his momentum with his arm is going forwards her moving a single step in is going to put her easily in range of his elbow. It's not gonna require her close more distance since she's already close. Yes he has longer arms, but in this scenario that doesn't mean much.

I also think it's amusing he thinks she's attacking with her blade, rather than simply keeping his staff busy :P

Anywho. My poing is while he can do the fulcrum movement+attempted grab, her strike isn't meant to just harm his arm, it's strong enough that it should hit his right elbow to the right, bending his arm slightly around her wrist with the movement.

Sorry if I didn't describe this clearly enough, I'm admittedly not as good at hand-to-hand combat as I am at weapon wielding or magical.