First, if your rares break, they simply get put to the merchant board now. So it wouldn't be gone forever, itd be there with 0/0 dura, just waiting to get repaired.
Second, just use a normal weapon to kill mobs until this gets fixed. Its not an "urgent" bug. Just an inconvience that makes the feature not as great. You are still able to do jobs and still able to get materials. Just be careful what you have equipped.