Lightsaber Mastery skill not unlocking.

As far as I know you need to unlock double jump to get lightsaber mastery.

^And I can now confirm that is indeed true. As soon as you get to where you attain the double jump skill in Kashyyyk, the very next Meditation Circle you will see Lightsaber Mastery appear in the Lightsaber skills tree, along with the final two life and force capacity skills. I highly recommend you farm and save at least 7 skill points so you can buy all 3 of them before taking on Ninth Sister, because she comes up soon after getting double jump, and there's really no places to farm skills there.