Artisans can enhance your equipment. The amount of gold and items required is different for each piece of gear. Some weapons and armor also have skills attached to them, the benefits of which can be enjoyed whenever they're equipped. Upgrading equipment can increase or change these skills. Weapons can also change into entirely new types by being upgraded.
Many of the items found in treasure chests or dropped by enemies are completely random. If you're lucky, you may find something rare! There are also mystery weapons that cannot immediately be equipped. You must first get them appraised in the town.