I am of the opinion that these sort of "special movements" must be handled narratively during the fight.
And I do, but technically "gain the advantage" would just be narrative. In fact, most of our rules could just be narrative. I think iconic things having crunch is fun. Having the option spelled out, even if it is just "on high" guidance when it comes to spending advantage and threat in lightsaber combat, would be welcome by me and my players.