Make items that you know the type of but not the bonus still show as identified.
For example, Amulet of Perseverance.
You find one and identify it, and you see the exact stats. However any future ones you find still appear unidentified.
So if it was a platinum amulet for example, even though you've identified one, you'll still see "platinum amulets" lying about, because each amulet can have a random willpower boost.
I think any such items should show up as semi-identified.
So they'd be amulet of perseverance (+?) in your inventory. So you know what it does, but you don't know the exact bonus until it's identified.
Same should apply to anything that has a random bonus and thus shows as unidentified even though you've identified one before.