I stopped reading after this part.
I've never heard anything funner in my life. If you don't have Darkside going 24/7, ESPECIALLY when outside of Grit, what you're doing is wasting so much MP by regenerating your MP over the cap, and then wasting your buff times by toggling Darkside between gcd's instead of an actual oGCD skill. If you have Grit off, Blood Weapon will carry your MP. While it's down, you simply lay off the Dark Arts spam a little whule using syphon to keep your MP going. Once it's back up, it's back to DA'ing every single souleater and C&S you can.
You talk about having 'mastering' Drk, yet what you're doing is the silliest thing I have seen any Drk do yet, and I've seen Drk's do some pretty silly things. The goal for a Drk's MP is to keep it floating. You NEVER want to max out, and you NEVER want to hit critical low point without a way to spike it back up. In other words, you never want to let Darkside fall off due to complete depletion of MP, and you never want to over regen your MP, or let it sit at cap. Syphon alone can prevent this, and outside of Grit, Blood Weapon will make sure that never happens. As for sitting at cap, Darkside alone should prevent that, but if you have anything over 5.5k MP, you best Dark Arts something, or throw out a Passenger, which I do literally on cooldown when I have Blood Weapon going, on top of Drk Artsing every Souleater.
Also, no matter what you seem to think, dropping Darkside for ANY reason at all while you're capable of hitting something, is a DPS loss. So yes, you're sacrificing a LOT of your DPS actually, and are likely wasting a lot of your MP as well every single time you enable Darkside. In every fight right now, dropping Darkside for anything is a waste of MP, because nothing stays out of your attack range for long enough for the Darkside ticks to outweigh the cost of throwing it back up, excluding maybe Bloody Fuller in Ravana. You have plenty of time to prepare for that however.
P.S. Blood Weapon is your main damage buff outside of Grit. Using that without Darkside on is the most foolish thing you can do.
P.S.S. I decided to read the rest, and those Warriors you went up against were likely very terrible, probably didn't utilize Berserk as much as they should have, and probably didn't know how to stance dance. Which in that case, they were playing entirely defensively, though with very questionable performance.
They do, it surprises even me. I take whichever boss I'm on, power slash, Dark Arts power slash, maybe power slash a 3rd time if I think I need it to push my enmity more, then drop Grit and never turn it back on again. Rotate my CD's to make the healers job a bit easier, and just go completely ham on Blood Weapon and all out assault. Often there are times where my bosses HP is much lower than the other, so I tell every DPS to go on the other boss, and I wind up either finishing my boss off on my own, or getting it low enough to where both bosses die at almost the same time. (And this starts from as high as 15% HP left on my boss)
But well I mean even as a Drk, I got all 4 floors cleared only a few hours after the patch hit.