This mod reduces armor rating to x% to increase damage taken from physical source. 10%, 25%, 35%, 50% and 75% versions available. Try different versions until your character takes relatively challenging amount of physical damage (keep in mind what level of gear you got made of what materials).

To prevent confusions: DAMAGE IS REDUCED TO X%, not by. So, to 75%, means 100 armor rating will be reduced to 75 (not to 25).

This mod is for those who end up with very low physical damage taken but still relatively high damage taken from magical sources.

Be advised this isn't an overall physical damage reduction, armor rating is only 1 factor amongst many other before final damage is calculated. If you use mods that modify enemy damage, crafting materials, items, then you may end up with undesired effect from 75% or even 50%. If even 10% version results in single digit damage taken, then you are likely using an insane cheat mod or a lot of stat buffing mods, or both.

My personal reason:

With zero mods, I started a new game on Nightmare difficulty after some years, finished prologue area, then in Haven I syncronized with the Golden Nug crafted tier 4 heavy chest and head armor with tier 1 crafting materials (Iron in primary slot --> low armor rating), and I ended up taking 2 physical damage from same level generic enemies but 200+ magical damage. Which brought me to the conclusion that armor rating is broken in this game, and I've not seen any mods that allow to alter this factor. Even with difficulty increasing mods, I increased the enemy damage by 20x (that is 2000%) which then made them hit me for 20 damage, and then I took well over 1000 damage from magic damage. With armor de-equipped, I begun to take 1000+ damage from physical source, which means, armor rating is not only broken but falsely designed equation for the game, especially if heavy armor gets crafted with tier 4 materials.