A weapon engraved with a Rune of Cleaving has the Armour Piercing special rule.

A weapon engraved with two Runes of Cleaving has the Armour Piercing special rule, and additionally grants its wielder +1 Strength.

A weapon engraved with three Runes of Cleaving has the Armour Piercing special rule, and additionally grants its wielder +1 Strength and the Killing Blow special rule.