Accessories offer a wide range of passive bonuses and resistances. Rings often provide elemental absorption or immunity, which can be incredibly powerful against magic-heavy enemies. Bracelets might boost stats like Speed or Attack. Mantles increase your unit's physical evade chance.
Other accessories include Shoes (boost movement or jump), Capes (evade), and various unique items. Always consider what accessory best complements your unit's role and the challenges of the upcoming battle. For example, a 'Reflect Ring' can turn enemy magic against them, while a 'Germinas Boots' can give a crucial movement advantage.