How does armor piercing over 100% work?

So I’ve been trying to understand armor piercing and I noticed that for example, if you used a weapon like Bloodreaper’s Claw which is 45% piercing along with The Blades of Nadaan devotion that doubles armor piercing and a Blessed Whetstone you should end up with 135% armor piercing (45% * 2 * 1.5 = 135%). Does that mean that if the weapon hits for 100 base damage it would do 135 piercing damage or does armor piercing cap at 100%?

It caps at 100%.

“armor piercing” is physical to pierce damage conversion. So you can not have more than 100%.

It’s not, armor piercing is a different mechanic. Armor piercing converts last, I think on hit. There is a pierce conversion which I’m not sure is used, but as with all damage conversion, it occurs before armor piercing.

You’re not wrong in that it can’t go over 100% though, just saying armor piercing is not necessarily the same as conversion.

Yes, armor piercing has the lowest priority. That’s why build around Harbinger set works well - 100% physical damage is converted into chaos damage (with Abominable Might proc, that has almost 100% uptime), and armor piercing property on Harbinger of Eternal Suffering does nothing (and dont reduces your DPS).

See this thread:

In particular post #13 in that thread.