I appreciate you responding point-by-point. It's a step up from the usual quality of discussion on these forums.
(from skill points page on my level 45 alt pirate)
A standard cutlass combo without any boosts to combo attacks or bladestorm, with full investment in cleave, flourish, thrust, and bladestorm, does a base level of 2973 damage at its higher margin
A standard cutlass combo from Cursed Blade of Yore with the same skill point distribution does a base 3549 damage.
Rank three critical strike - per my testing of thunderspine - is likely a 30% chance of a critical hit for each of the weapon's strikes. It follows that a rank 5 critical strike would then be a 50% chance of a critical hit. A critical hit does twice the damage of a normal hit. This is effectively a 50% damage buff to all attacks over a long period.
(per Charles Warmonk) every "Powerful" skill increase is a 5% damage buff to the sword's attack - bringing Jack Sparrow's Blade's actual attack to 103.2, about 10% more than 93 (technically it's only 10 percentage points better if we use a 100% scale.. but the difference between that and the actual value is within 1%).
Applying the buffs from Powerful rank 4 and critical strike rank 5 to the standard cutlass combo's damage of 2973, we find that the damage from full combo + bladestorm for Jack Sparrow's Blade totals to 4841.
I didn't bother factoring in the cleave boost.
Even without the cleave boost, Jack Sparrow's Blade is 27% more powerful than Cursed Blade of Yore
And with rank 3 health drain, 11% of that damage will come back to the player. Since players attack much faster than NPCs do, this added ability makes the player nigh-unkillable just as it does on World Eater Blade. This is the best sword in the game.
I concede that a sword like Krakenslayer or Leviathan still has its place in scenarios like farming the gold room with friends (though it's worth noting that most looting takes place at bosses now... and the majority of people who do loot in the gold room prefer to simply use grenades by themselves than broadswords in a group). But isn't a sword that retires every other single-target sword in the game enough of a problem already?
Drain health is only "unnecessary" because players are overpowered relative to all NPCs except a select few, as you pointed out. Surely the answer to this problem can't be to make players even more obscenely powerful with additions such as this. Against very formidable enemies or other players in PVP, that drain health makes a tremendous difference - as anyone with WEB will attest to.
My point about Pirate Blade remains. The reason no one expends the effort to get it is because the costs to getting it significantly outweigh its benefits. People who unlock the sword do impress me, but like anyone, I have to wonder why they thought it was worth it.
FYI, the imbalance in power between the legendary cursed has stopped people from finding certain legendary sabres. Why do you think there are only two Ruby Curses out there? Finding one is very impressive, but the sword's power pales in comparison to Sapphire - which is much easier to get and consequentially has been looted dozens of times. It's a simple cost/benefit analysis.
I take back my final comment. Not everyone I disagree with is suffering from cognitive dissonance. However, I do believe that someone can not both understand how powerful this sword is and sincerely think that it is balanced.
EDIT: I've invested too much time and energy into this conversation at this point and need to stop and move on. Thanks for hearing me out.
Just be greatful for what the game devs give us because they are the ones who put their backs into it to remake this game and work it 