Phoenix Mail:

The ruler unit of the wielder of the Phoenix Mail gains +1 Defense and immunity to the negative effects of the Tundra terrain type. Additionally, rather than making an attack, the wielder may instead double their defensive bonus until the end of the battle. While this increase is in effect, all units that attack the wielder take 1 damage. If equipped to a character with less than 1 prowess, their speed is reduced by one.