Damage type

Every damage source has a damage type associated with it. There are seven types of damage: melee, bullet, shrapnel, fire, plasma, acid, and piercing. Each is, of course, different from the others in some way, though some are more common than others. Also, resistances apply to each damage type separately.

Melee Damage

For every point of armor the target has, they take one less damage per hit. Melee damage cannot destroy walls. It is dealt by almost all melee attacks.

Bullet Damage

Bullet damage has the same technical properties as melee damage; protection applies normally and bullet damage cannot destroy walls. Bullet damage is generally dealt by weapons that use 10mm ammo.

Shrapnel Damage

For every point of armor the target has, they take two less damage per hit (although this goes to zero for the player if they have the Army of the Dead master trait). Shrapnel damage cannot destroy walls. It is limited to most shotguns.

Fire Damage

Fire damage treats protection normally (one less per point), but can destroy walls. Additionally, fire damage is the best for gibbing enemies. Despite the similar names, there is no connection between fire damage and Fireangel.

Plasma Damage

Plasma Damage halves armor protection, rounded down. Gibbing is easier. Most weapons that use power cells do plasma damage. Additionally, several enemy projectiles cause plasma (even some you may not expect).

Acid Damage

Acid damage damages armor durability twice as much as other damage types. Gibbing is easier.

Piercing Damage

Piercing damage ignores all protection and resistances. However, it cannot destroy walls and is no better at gibbing that bullet damage.