It doesn't matter which one you have, as long as "the force" is strong within you.

But, I'd take the lightsaber cuz it's more classy to kill with a sword than shooting someone.
If the light saber and the phasor have their frequencies exactly 180 degrees out of phase, then they would observe destructive interference and simply absorb each other's energy. Thus, it would block. I'd take Magneto's mutant abilities any day, it's stop them both.