I agree with having different forms of curses on a weapon. I especially like the idea that is present in ADOM in the form of "backwards" effects from a cursed item, such as the cursed potion of invisibility acting like a potion of blinding instead.
Also, I would like to see curses that aren't all bad. For example, you find a pair of bracers with forked lightning etched on them. When you equip them, they have a binding curse on them so you are unable to unequip them, similar to the current curse effect. However, they also have another curse on them. When ever you strike a foe with unarmed combat or a conductive metal weapon, you apply a bonus percentage of electrical damage to your attack (say 25% extra damage) but it also has feedback which damages you (say 50% of the electrical damage). So for example, you attack with your weapon and it then rolls a 1d(result/4) which does that much damage to your target and half of that to you.
Or it could be a masked effect that appears to be beneficial until you use it in a certain manner. For example, you find an amulet of magical reserve. When you first equip it, it can be unequipped as normal and it seems to lower the PP cost of all your spells. However, what it is actually doing is draining that extra PP into itself until it reaches it's maximum charge and violently erupts in magical energy.
As I see it, not all curses are flat out bad (though some, like the stat draining ones, should be). However, they should definitely add more character to the game than simply being stuck.