Based on My result I believe it's definitely less then 40 given 734 Parry Drk.

1001 Hits 43 swings, 221 parries.
221/958.
23.06% Parry rate.
Could a) divide the whole rate by 734.

B) subtract the 354 base % rate then divide by 380.

Either way that's ~31-34. Give or take a point.

I would wager base Parry rate for War/Drk is actually 11% or close to 11% and not 10%.