Nah mine was PvE testing and I totally forgot about PvP and Shields, my bad.
The tooltip is roughly 9k if you don't stack Spelldmg that high.
In PvP, the dmg is always lower than tooltipdmg or you ignore the whole spell resistance. (another skill waste for just a bit more dmg.)
Ain't nobody got time for buffing a single shot in a fight.
And I doubt that the 21k hit was uncrit
I like the skill in theory, but i would add a stamina morph that scales with wep atack/crit and reduce the number of atacks to 3-5 and the dmg a bit.