Talk:Blade of the Ruined King/@comment-5489694-20130105053227/@comment-24.247.113.245-20130106033157

All physical damage is mitigated by armor, from any source. Hence, all physical damage benefits from Armor Penetration. Armor Penetration does not increase damage, it reduces damage reduction, ergo having % penetration would increase the damage dealt to the target, but would not increase the healing from the active.

This is elementary stuff, you could've answered your question by looking up the armor page.