Repair is one of Thaumcraft's special enchantments. It allows selected equipment to repair itself by using vis from a carried wand or similar device.
Thaumonomicon entry Edit
"This enchantment slowly repairs the durability of items by drawing vis from the aura. The higher the level of the enchantment, the quicker this takes place. This enchantment can only be applied to items made with Thaumcraft, and even then not all of them."
Repair is placed on items like any other enchantment: Through the enchanting table, the anvil (with a book), or by Infusion Enchanting. It can be applied to most of Thaumcraft's mod-specific armor and weapons, from Thaumium to Thaumium Fortress Armor and elemental tools. However, it is incompatible with the Unbreaking enchantment, and it can't be used on void-metal items or Void Thaumaturge Robes (which already self-repair). Repair only has two enchantment levels.