Mending Book

A Mending Book is a rather useful item in Minecraft. Using said enchantment on a tool or weapon will make the tool/weapon automatically be repaired by a specific incremental amount when picking up Experience Points.
Alternatively: Something Grian will never get.

"The ocean provides, I know it does. That next book, I know it; I can feel that it will be mending!"
*It was not a mending book.*