There's something a little strange about how the Xala'shar vanquisher special attack interacts with Perseverance of Peri'el. It messages like the barrier is doing it's thing:

A hulking Xala'shar vanquisher slams the dark steel plates attached along the length of its arms together before quickly drawing them against each other with a metallic screech, sending a shower of burning blue sparks hurtling towards your face!
You are aware of the injury to your flesh, but it cannot harm your vitality through your Perseverance.
Moving a moment too late, the blinding shower of sparks cut into your face and eyes with the savagery of an acidic dagger, piercing deep into your flesh. The burning bite of the metallic slivers tear into your eyes with unforgiving ferocity as the world goes black around you!
[You're bruised, incredibly balanced and overwhelming your opponent.]

But it still inflicts a small amount of vitality loss. This doesn't seem to be from the bleeding, as it happens immediately when the attack is resolved (see "You're bruised").

So it needs to either successfully block the vitality loss, or not message as though it has.

Thanks,
-Life Sustainer Karthor