I've always thought something like this would be nice.. If I recall right, there used to be a note on every item's deion how rare it was, but a ton of items were listed as 'special,' which really wasn't helpful at all. It basically just let you know that, hey. It came from some act other than buying it from a shop. Even many retired items were still shown to be special.
'S one reason the rarity game was always so hard to win..
I guess it'd probably be a huge pain to do, but some kind of revamped system to show how rare an item is would be awesome.