In all honesty it wouldn't seem particularly broken or unbalanced to have a Flourish that causes Dispel, of course it can get resisted just like Violent Flourish. I imagine it to be very similar to that one, physical accuracy for the hit to land, magical accuracy for the dispel effect to occur.
Altough that would kinda break consistancy with Flourishes... all 3 groups have 3 flourish inside, making so one of those groups has 4 would make the OCD in me cry!
PUP already has a mana-free dispel that's pretty effective btw, without any particular restrictions.