Armor Piercing stacking and Blades of Nadaan questions

So I’ve decided to try out another melee. I’ve taken over an old Blademaster I hadn’t finished, and converted it to a DW damage machine. She’s only level 79, but feels strong so far. I picked up Blades of Nadaan and had some surprises from it.

First, I noticed that Cadence had physical damage at about 11% the pierce damage, but when I removed one blade, that percentage increased to about 20%.

I then removed Blades of Nadaan, and with 1 blade, the damage types were almost 50/50. That is with a weapon that has 33% piercing.

Looking at the results, am I right to say that armor piercing, at least on weapons, does not add, but will apply to the remaining physical percentage one after the other? Then the Blade of Nadaan only applies to your highest individual piercing percentage?

So I figured I get 33% from 1 weapon. About 55% from 2 weapons, and about 88% from 2 weapons and Blade of Nadaan. Is that an accurate description of how they stack?

That seems to be the only thing that adds up for all the ways I’ve looked at it. It’s hard to figure exact numbers given added +'s on the skill, and weapon damage. But if 2 weapons added up, then physical damage with Blade of Nadaan would hit 99% or higher, depending on whether it applied to all or just 1 weapon. If Blade of Nadaan applied to the total armor piercing, then that would also always hit 100% with 2 weapons, which it does not, even if they were added or applied to the remaining amount for the 2nd weapon.

The above description seems to be the only one that adds up mathematically, but then again, I’m new to all this. Perhaps someone has a better understanding. I could possibly see that Blade of Nadaan could take my 55% and apply it again with the remaining physical damage so I end up with 79.75%.

Edit: I just realized I’d get better numbers if I stripped away all my damage bonuses and looked at raw weapon damage numbers.

Pierce % from two weapons don’t stack. The % only applies to hits with that weapon.

Oddly, the percentages coming from Cadence were much different with 1 weapon and 2. Now I think about it, it’s probably because of the skill Dual Blades.