Unique items do need some sort of change.
Either make them easier to repair, or don't degrade as fast, or don't degrade at all. (Can be countered with a higher chance of lost on battlefield or some such. However, if lost on battlefield, there should be a high chance of someone else finding it).
Unique items should be something that sticks around in the game and are worth something more. They should be a symbol of prestige and notability, not a simple tool which causes extra effort from both advys and nobles to keep from being destroyed. If I get a unique item, I want it to stick around and not have to give it up at 40% condition to give it a small chance of being repaired.
There should be incentive to push the unique items to a high prestige, by holding on to them for a long time. However, right now it is simply difficult to do so even though some characters would want to have them for RP or other reasons. If they became perhaps harder to find, but easier to keep, (so become more valuable, but more sustainable) I think the system could be fixed.