I think I'm going to go with #3. That way it offers the "bastard sword" option (old school version). I won't allow arm manipulating the shield to be usable for another weapon.I'd go with option three. They can use it one handed and with a shield but if they want the benefits they need to use it two handed. When they suggest strapping the shield to their arm I would allow that but then rule that they can't properly use the shield for it's benefit so long as you're fighting with both hands on your lightsabre.
It also gives incentive for the Quick Draw talent. It seems the simplest option