Armor Piercing

Armor penetration is an effect found on certain weapon Enchantments designed to ignore a certain percentage of the target's physical damage resistance.

Mechanics

Armor penetration reduces the target's armor resistance to your attacks by a flat percentage.

Unlike damage resistance debuffs, if the recipient of the penetrating damage has resists over the cap of 75, it will never be treated as higher than 75. This means that it is impossible to reduce the effectiveness of armor penetration (unless you have no armor to penetrate).

Examples

You have 33% armor penetration on your dagger, and your target has 75 resistance to piercing damage. Your attacks always treat the target as if they only had 50 resistance instead.

The same target returns with 100 piercing resistance (effectively 75 with the cap). You will hit them as if they had 50 resistance, just like before.