Maybe the sunsword isn't so nice a guy afterall, because it can't be yielded by players who are using the dwarf race while in the Castle Ravenloft dungeon.
Reproducing is pretty simple:
1) Be on a character who is using the dwarf race
2) Try to pick up the sword in Castle Ravenloft
I've experience and seen this bug happening while as a fighter (both dps and tank), but I'm not certain if it applies to other classes.