I prefer cursed items that are just that: cursed and nothing else. Such objects would not provide a positive ability or bonus to offset their albatross. Remember that they are supposed to be tools of adversity in the service of drama. Any benefit these ill-starred instruments may provide to the player should be gained through ingenuity (e.g., using the bag of devouring to dispose of an evil artifact that is a far greater threat or tricking an NPC into accepting a jinxed magical sword that can only be separated via voluntary exchange).
