Of Kings and Men
Armour as Damage Reduction
In truth, most of the rules for Armour as Damage Reduction are exactly the same as described in the books. However, here are some key differences:
Magical armors and bucklers add half their enhancment bonus, rounded up, to DR. Magical Items provide normal bonuses. Magical Shields add their full enhancement bonus to DR.
Natural DR and Armor DR stacks, as do all other things that bestow DR, unless expressely said not to stack.
Critical hits ignore half DR if a non-piercing-weapon is used or all DR if a piercing weapon is used. (Feedback on this is requested.)
All attacks that would normally be reduced to 0 by Armor or Magical DR instead cannot be reduced to below 1. Natural DR can lower damage beneath 1. Bludgeoning attacks deal a minimum of 2 damage, because Bludgeoning weapons are the best weapons to use against most armours due to their likelihood to deform it and cause injury. Natural DR can still lower the damage beneath 1.
Piercing Weapons ignore 2 DR/-. Magic piercing weapons ignore 2 + their enhancement bonus DR/-. All other weapons ignore DR up to half their enhancement bonus.
Arrows can be purchased in any mundane damage type. Standard arrows become armour-piercing, bludgeoning ones are hammerheads and slashing ones are crescents.
These are the profiles for the different arrows:
Armour-Piercing – arrows and bolts with long heads made specifically to pierce armour. They deal piercing damage and gain the same benefits as piercing weapons in overcoming armour damage reduction.
Slashing Arrows – arrows and bolts with curved, crescent heads made to tear flesh. They deal slashing damage.
Hammerhead Arrows – arrows and bolts with square, hammer-like heads, made to deform armour and helms and cause blunt damage. They deal bludgeoning damage.
Cage Arrows – armour-piercing arrows and bolts with a special cage made to house a burning rag, a vial, or some other small object.