Mysterious magic items - When magic items are found on the world map, the characters don't know what they can do. They just know it's a magic weapon, armor, etc. This would allow the Identify spell to be used. Perhaps allow it to not use a spell slot (ritual cast), but it still needs to be learned and prepared for the day. Even some vendors may not know what an item they have does, so you can have a mix of known magic items, for their full price, then unknown ones, which are at a significantly reduced price.
