Despite lacking Plate Mail Armor, the Romans have a civilization bonus giving their infantry units double the effect from Scale Mail Armor and Chain Mail Armor, more than compensating the fact that they cannot research the technology.
Armor made of large metal plates was the best defense obtainable against missiles and hand weapons. It was stronger and absorbed more energy. Large sheets of hammered steel were fashioned to fit the wearer's body. Making plate mail armor became an important craft. Specialists in Italy received orders for armor from all over Europe. The booty from battle or tournaments included valuable armor. Armor required regular oiling to prevent rust and this was the duty of squires indentured to knights. Plate mail armor appears ponderous today but was actually reasonably light and well designed for mobility. Athletic knights could perform handstands wearing armor. Knights could mount their horses without much difficulty and did not require cranes for a lift.