Item repair

[FakeTruth]

I think you should use HOOK_CRAFTING_NO_RECIPE, because that way no unnecessary hooks are called.

Figure out whether there are two of the same items (and only those two) in the crafting grid.

Then use the ItemCategory:IsTool( ItemID ) function to determine it's a tool

Then set the output item to have the ID of the input items, but with less damage (use the damage formula thingy)