Its just a force taunt, Challenging call and Taunt don't generate threat. My biggest problem with tanking and threat management is the lack of skills that explicitly generate threat (i.e. hilt strike) on top of threat generated by damage. The build I currently run so far (successful Taral V and False Emperor HM) doesn't have Guardian or Overhead slash. When I get home I'll edit to post my build, but it focuses on maxing Force Sweep's damage to generate AOE threat. Its one form of the Defense/Vigilance build. Also something to note: If you don't use Guard, you should. It helps redirect damage away from a DPS target to you, as well as solving part of the DPS threat problem. Just make sure that you get a feel for the max distance you can be from the person you are guarding as its range is not that far. I suggest putting it on the person you are having the hardest time holding agro from. I know this sounds strange coming from a tank, but you don't HAVE to hold agro on everything you are fighting at least in flashpoints. 1 DPS can tank a strong or normal mob fine while they blow it up as long as you are holding the champion/elite.