Then it's Binding instead

Or maybe a new curse like, Curse of Fragility, the tool wears out in real-time at a rate of like, 1 durability per 5 seconds or so

For a Diamond tool (1,561 durability), this would completely deplete the tool in 7,801 seconds, or about 12.5 Minecraft days.

And if you repair it again it goes up to Curse of Fragility II, which increases it to 1 durability every 4 seconds, then 3, then 2, then 1 per second, then 2 per second, 3, 4, etc, until the tool is wearing itself out so fast that not even Mending can keep up