NOTICE: I am no longer developing for Forge. If you ask for a Forge port, you will be ignored.
Damage Threshold (DT) is an alternative way for armour to reduce incoming damage. Vanilla uses Damage Resistance (DR) which reduces damage by a percentage, while DT reduces damage by a flat amount, which makes it easier to calculate how much damage you'll take from any given weapon.
If anything needs adjustments, let me know. I highly recommend pairing this mod with NoDamI and CombatEdit.