Ah! I understand. I'll add the card image.
Edit: Images are updated.
Thoughts now?
When it's broken, you have to wait 1 turn to restore it, like Phoenix?
I think it would be better if you have to wait, so it would make sense to equip 6 Kagero and replace it instead of repair it if you don't want to wait 1 turn.
Other than that, there are some calculations to do, considering probability of breaking and weighting damage over a certain number of turns.
After that we can tell if the weapon is balanced or not.