My personal favvourite is a belt of gender chanching - which also appeared in BG, which left a mucky taste in my mouth after that male Ogre was killed …

Another personal favourite of mine is the "talking sword".
Which need not be a cursed item, but that solely depends on the "personality" of the sword.
An example could be a "pacifistic sword", which avoids comnbat at all costs, for example.

By the way, Jay, have you taken a look at the "negative attributes" of TDE 3 ? I think they'd fit nicely into that theme, and they're imho unique.

Unfortunately they are heavily reduced in TDE 4 : They are no more obligatory, but instead they are used as a means to receive more "generation points" in character generation. That's how they are usually used.