Damage 1.0/Physics Impact Damage

Physics Impact is the damage type most comenly referenced to as "Armor Ignore" (there actually is no such thing). This is the damage type used by weapons such as the Paris, Boltor, Kunai, and many other weapons labled as "Armor Ignore" damage type.

The Physics Impact damage type is most often included in enemies list of damage types to NOT apply armor to, however, no enemies have specific multipliers to increase or decrease this damage type, so Armor Piercing damage would be either equally more effective than it against most targets (all excluding light infested).