Weapon strikes typically have one of the three following types: Piercing, Bludgeoning, or Slashing.
For each of these, there's a Physical Resistance that halves the damage that sort of strike does. For example, skeletal Longdead fellows don't have much that can be pierced, while the puncturable organs of the Soulless don't really matter to them. A plant only really minds being cut. A statue is easier to smash than to bisect (or poke holes through). These different traits are known as Pierce Resistance, Blunt Resistance, and Slash Resistance.
Physical Resistances only apply after Protection, and the resulting number is always rounded up. The resistances cannot bring damage from a hit down to zero. Notably, Slash Resistance conflicts directly with the damage bonus Slashing hits get.
Pierce Resistance can be applied by Death magic; Skeletal Body (a Level-1 Alteration) is a self-application by 1 mages, while Skeletal Legion (a Level-6 Alteration) lets 4 mages with 1 (or 3 mages with 2) apply it to their entire army.
All three Resistances can be applied by Water magic, along with Affliction Resistance; Liquid Body (A Level-4 Alteration) lets 1 mages self-apply, while Wave Warriors (a Level-7 Alteration) lets 3 mages with 1 (or 2 mages with 2) apply it to a large swathe of their battlefield.
Earth mages may apply all three Resistances to themselves without drawbacks, through the Temper Flesh spell (a Level-4 Alteration). This also provides 5 Fire Resistance. All three Physical Resistances may also be applied to the Bless of a Pretender God with at least 8, through the incarnate Fortitude effect.