Excluding key items received from advancing the story, nearly all items can be equipped. Such equipment includes weapons, armor, and accessories, and can be found by defeating enemies, finding treasure chests, and completing quests. Each item can be set from the Equip tab of the menu screen.
Items come in one of three rarity values indicated by text color: white for Normal, purple for Rare, and orange for Unique. The rarer the item, the greater the stat boost the item gives. However, Unique items cannot have an Item Drop Rate stat boost.
One Fighter's Trash...
Some items may not be suitable for battle, but still have a variety of uses! They can be used to increase certain stats or sold for high prices. Keep that in mind when cleaning out your inventory!