Whilst writing this it has suddenly occurred to me that this may be possible but I've just not worked it out yet, if so feel free to call me a noob
Say that I have in my possession some -2 items, either they are that way from battle or were purchased like it, and I then move into a fief that is able to produce those items to a +1 quality. For a percentage of the items' base price I think we should be able to have the items repaired up to that quality.
This will get rid of all the annoying low quality gear that you end up with after a fight, but in a sensible way.
Also.... did I just advocate a form of upkeep????