Many Dwarf warriors bear weapons forged of gromril. Such fine weapons, family heirlooms passed down through many generations, possess remarkable sharpness and durability.
A hand weapon carried by a model with this special rule has an Armour Piercing characteristic of -1.
Note that this special rule only applies to a single, ordinary hand weapon. If the model is using two hand weapons or any other sort of weapon, or if their hand weapon is inscribed with any Weapon runes, this special rule ceases to apply.