All Equipment Items have different characteristics and Levels of Rarity. Gloves, Boots and Weapons affect the Offensive stats of your Units, while Helmets, Shields and Armor will augment the Defensive statistics. Charms can affect either the Offensive or Defensive characteristics of your Units, depending on the Charm in question.
The higher the Level of your Equipment, the better its effects will be. To compare an equipped Item with a second one in your inventory, simply tap on the Item you want to compare and see the differences.
Hero Equipment is upgraded using Shards, which are the fragments of other pieces of Equipment. You can break any piece of unwanted Equipment into Shards, but be sure that you really want to break the selected Items before proceeding: Once broken, an Item cannot be repaired.
Higher Level Equipment requires more Shards to be upgraded and Upgrade Times are longer. However, Boosts can be applied to the Breaking\Upgrading process to save time.