Armor that reduces damage would only work if you took each armor and designed three sets of stats for each armor. One set of stats for each type of weapons blunt, slashing and piercing. Also you need a set of hardness vs each type of weapon.
Chainmail Armor being the best example would have almost perfect reduction to damage from slashing with minimal subdual damage. It would have no damage reduction from blunt weapons and then you have piercing weapons would medium reduction for both damage and subdual damage.
Next you get into the idea if you had damage reduction you would also need hardness factors and hp for the armor, because the damage reduction would assume that the armor would be absorbing the damage. Chainmail would have high hardness vs slashing, low hardness vs piercing, and med to high vs blunt.
just my opinion