Vader cuts off Luke 's hand and then tells Luke that he is actually his father , Anakin Skywalker . Vader loses ground as Luke lands blow after blow ; Luke knocks Vader to the ground and severs his father 's mechanical right hand . With the Emperor ordering Luke to strike Vader down and take his place , Luke glances at his own bionic hand and realizes he 's on the verge of following the same path to the dark side as his father .