I understand how armor piercing works numerically, but the interactions are confusing and vague.
How does it apply to skills?
For example, how does it apply to Cadence, Forcewave, and Grenado?
I choose those three skills because Cadence is a default weapon attack replacement (with bonus physical damage), Forcewave is a physical damage skill with %weapon damage, and Grenado has physical damage but no %weapon damage.
Basically, does armor piercing apply 1) only to the physical damage from default weapon attacks, 2) to %weapon physical damage, or 3) to all physical damage?
If a skill has a % weapon damage component, all of its physical damage is applicable for conversion. If the skill does not have a % weapon damage component, armor piercing doesn’t apply.
So for those three skills…
Cadence - base weapon damage and bonus physical damage get converted
Forcewave - base weapon damage and bonus physical damage get converted
Grenado - nothing gets converted
As an added note, armor piercing conversion happens AFTER other conversion. For example if you had a weapon that does 100 physical damage with 50% armor piercing and you had 50% physical to elemental conversion, you would do 50 elemental, 25 piercing, and 25 physical damage.