I've had a few unique items. My experience has been the following:
One item I lost in a random monster battle.
The rest have all degraded away.
I have one item currently and it'll probably end up degrading away as well. The repair aspect is just too much of a hassle unless you happen to have an reliable advy you can call on. Even then the item can degrade away if no sage is found.
So in general I just don't bother with unique items. They're just not worth the effort.
