hi, I had to look up what shelf-wear is, but my best guess is "normale Abnutzungserscheinungen," or "Verschleisserscheinungen" fits. Shelf-wear just refers to books, right? I don't know of a specific German word for that, but maybe someone else does.
Im acually selling an item (a toy) on Ricardo and although its new its not perfect condition so I wanted to say it had some shelfwear. Was thinking perhaps "Lagerspuren" und "leichte Kratzspuren" because I bought this toy new but I cant sell it for new.
On Ricardo, you could opt for "Neuwertig", which means as good as new.
However, in the case you describe, I would choose "Gebraucht" (= used) and then elaborate in the text the actual condition. This will save you getting bad rep if the buyer is disappointed.