Sorry for the mistake, I stand corrected.
I just read the first look at Gamespot.com, quit an old source if they dropped the whole arm-control device idea.
I had to get especially nerdy and ask how Darth Vader could take on an apprentice when he is himself the Sith apprentice to Emperor Palpatine. While your character is plenty evil-looking and wields a red lightsaber, company reps were quick to point out that he isn't a Sith at all. In fact, concept art shows the character wearing a sort of shackle on his wrist that Vader apparently uses to control him, so from the sound of it, there will be some ambiguity regarding your true motivations over the course of the game. You'll even have some control over the appearance of your character, possibly extending to the color of your lightsaber, though again, LucasArts isn't talking hard details about this yet.