Sneak peek of the new Thief and Pirate

Hmm, not sure if I'm doing all the math right, but, ignoring ADS's damage boost, Thorns, and Boss Damage equips, and buff delays and Final Cut's own damage (a lot of stuff, okay, but this is just a simple calculation):

Phantom Blow is 105% * 6 hits, or 630% at 810ms, which is either 600ms or 630ms after Booster, but assuming 600ms, that's 1.67 Phantom Blows per second. Final Cut gives +40% damage every 40 of 90 seconds leading to an average increase, on non mirrored hits, of (1.4 * 40 + 50)/90, or about 1.178x, and with only maxed sharpness (total crit chance being 30%, with 5 base, and 1.4x~1.5x (1.45x average)) the average crit increase would be (.3*1.45+.7) or 1.135x, and then assuming 1.7x multiplier on mirrored hits for Final Cut, the average increase, I think would be (1.7*.7*40+.7*50)/90, or 1.976, as opposed to 1.7, so %/s would be 630 * 1.67 * 1.178 * 1.135 * 1.976 = 2779.6%/s
Then post-Legend, I don't know if the mirrored hits are fixed at 70%, or if they just can't go over the regular hits, assuming the worst case, fixed at 70%, the %/s would be 630 * 1.67 * 1.178 * 1.135 * 1.7 = 2391.4%/s. This is like, a ~14% decrease in damage, in the worst case scenario.

But again, I'm not sure if I'm doing all the math right, and yes, the more % damage and % boss damage you have, the more this will affect you. Also, this is lower than post-Union Bishops, but there's really no comparison, given the different multipliers and attack/magic attack and other stats, which ideally should be cancelled out by the multiplier, but it's not.

The main dps decrease would be the the reduction of the effectiveness of % boss damage on dualblades.
Right now, having 30% boss would make your regular hits 1.3x as strong, and your mirror hits 1.69x as strong.
After legend , it would only be 1.3x on mirror hits, which reduces DPS quite a bit.