Add post-penetration defenses into the in-game stats on the selected enemy.
Make it so that we can see both the pre and post penetration def stats of our enemies in the portrait panel. The knowledge of that is something one calculate on their own, so why not follow the clarity, and just make it a little easier. Putting the post pen defs, in brackets, after the original ones would be simple, and effective. Same should be put into the description box (They take X% (X%) less dmg).