from leo:

unless I have dreams luck, tools with runes applied won't use anvil durability ever

Title is wrong, anvil don't take durability when repairing/adding enchantments to tools that have runes on them

close this one, it works as intended, I.. really just had enough luck to not break a damaged anvil with multiple tries, but testing it again today I can break them after applying a rune to the tool.

The dream’s luck was inside you all along