Combat Art

Weapon Arts or simply Arts are a gameplay mechanic introduced in Fire Emblem Echoes: Shadows of Valentia

Overview
Weapon Arts are special skills and techniques that characters can use in battle. Unlike Skills which are learned based on a character's current class, Arts are learned by using specific weapons. The more a character uses a weapon, they begin to learn new attacks with different properties from the standard attacks. They can increase range, deal effective damage against a specific type of enemy, or deal more damage. Once a character has learned an Art, any subsequent weapon that has the same Art as the ones a character has learned will be automatically usable from the start.