The rotate in the display of one shop. Brightwall smith sell 6 or seven different weapons, four are in the shop at the same time.
My first playthru... the Brightwall shop still has the same four weapons in it after the end, as it did when I first encountered the shop. They, in fact, do not "rotate" at all. Unless someone else can confirm this, in which case my game was obviously bugged.
But I encountered only one glaringly obvious bug (the frog statue in the pond of Summer House, the base is "made of water" for me and reflects like the water it's standing in.) in my first play-through.