Armory mail upgrades affect the hack armor of all human soldiers, Heroes and ships: those trained at the Academy, Barracks, Longhouse, Dock, Migdol, Fortress or Hill Fort. They do not affect myth units or siege weapons. Hack armor protects a unit against hack attacks, which are generally hand-to-hand attacks such as swords and axes. The armor percentage is the amount by which the attack is reduced.

Before civilizations mastered the art of forging steel, meteoric iron was among the hardest metals known, and the best for making weapons. Egyptians valued meteoric iron more than gold; King Tutankhamen was buried with several gold daggers but only one of iron. Meteoric iron has a high carbon content, which was difficult to duplicate even by Norse times. As such, a meteoric iron weapon that could hold its edge for so long was considered magical. The Norse sagas mention a warrior who straightened his sword blade with his foot, suggesting that the iron the Norse typically used was of fairly poor quality.