When real armor is hit, most of the damage is done to the armor, and and only concussive damage is dealt to the person, right?
In 13th Element, I planned for armor to have 2 variables: Current Toughness, and Maximum Toughness. As armor is hit, it's current toughness decreases.
So say your opponent is slicing at you with a sword or something and it would hit your upper torso armor.
When it hits, a random number is rolled for initial damage from the weapon.
This becomes divided into 2 variables, "Damage" and "Resistance" because you are wearing armor. Damage should be reduced if your opponent is tired (Low Stamina Percentage).
I created four formulas that explain exactly how damage to armor and person are calculated., but people are confused enough as it is.
It's basically a curved inverse relation between what condition your armor is in, and how much damage you take.
The more damaged your armor is, the more damage you take.
But it's a curve, so how effective your armor is changes slowly then drastically as you continue to take damage.