Is there any apparent reason that Silver swords/greatswords don't ever disappear from a vendor's inventory after you sell them? I sold some silver swords to several vendors (in Whiterun) and they are still in their inventories 30+ days later. Every other kind of weapon I've sold seems to disappear when a vendor's stock resets (after 48 hours or so), but the silver weapons persist indefinitely. Is this a bug or is it deliberate?