You are wrong that it could not be worse, it is merely temporarily unusable and will likely never be as good as new. 0/1 would be the worst as far as I can tell but it takes a long time and a lot of repairs to get there. I've been working an ax down to try and get there and I have managed to train from level 20 to 22 and still only got it to 17/17. That is a lot of repair, I tell you what!