A single hit will knock you out of the force sword special animation causing you to only deal minimal damage of the initial hit. This diminish the value of the sword greatly as it can’t special attack elites or other high value targets in a intense situations like a horde, the most valuable time such a ability would be needed.
Make it like the chain weapon where once the weapon bits into a target it finishes the animation or the target dies whichever first. I’d rather take the damage I took during the animation lock and do the damage. It’s up to the player to time the attack correctly.
The special attack should also grant warp charges.