Some attacks can penetrate armour with an ease that belies their meagre strength.
Armour Piercing (*)
Wounds caused by a model with this special rule (or who is attacking with a weapon that has this special rule) inflict a further negative armour save modifier as indicated by the number in the brackets, in addition to those for Strength. Unless specified, Armour Piercing only applies to close combat attacks. This rule is cumulative with other sources of Armour Piercing.
If a model has a weapon with the Armour Piercing special rule, only attacks made or shots fired with the weapon are Armour Piercing.