There are various ways to repair items in Advent of Ascension.
By using a Mending Table, the player can repair items by using Magic Repair Dust or Magic Mending Compound via putting them in the middle slot, and putting applicable items in the left slot. Magic Repair Dust will restore an item by 20% of its total durability value, while Magic Mending Compound will restore an item's durability to full. This does not cost any Experience.
This method is compatible with any item that has a durability value.
By using an Anvil, Crafting Table or the 2x2 crafting grid in the player's inventory, combining 2 of the same item will combine them into 1, merging their durability values (cannot go above max), along with adding an extra 5% durability. This costs Experience when done in an Anvil, but any enchantments the 2 items have are kept if done in an Anvil.
This method is also compatible with any item that has a durability value.
By using an Anvil, combining a damaged item with the primary material used to craft it will restore durability. E.G. Putting a damaged Limonite Pickaxe and Limonite Ingot in an Anvil. Doing this restores an item by 25% of its total durability value. This costs Experience to do so.
This method is only compatible with the basic tools/swords made with Amethyst, Bloodstone, Crystallite, Emberstone Ingot, Jade, Limonite Ingot, Rosite Ingot, and Sapphire. The exception to this is Crystal Carver, which can be repaired with any item considered a "gem".
The Mending enchantment can be applied to any item with a durability value. Doing so allows the item to absorb Experience orbs and restore durability.
Certain items like the Goofy tools will also restore durability on their own. However, other self-restoring items like Ice Armor or Rosidian Bow require other conditions to be met in order to regenerate durability.