Weapons no longer stick to your hand when cursed, because that just makes the game less fun and strongly discourages experimenting with random weapons lying around (there are good weapons out there, but the risk of either ending up with a bad welded weapon, having to spend resources to get it unstuck, or spending identification resources on making sure it’s safe) means no one will give them a try. Instead, replace that behavior with a variety of other effects:

• The weapon occasionally turns on you when you try to attack with it, hitting you instead.
• The weapon occasionally deals an extra 1d8 shock damage to you and your opponent when it hits, possibly breaking rings.
• The weapon wakes up any sleeping monster you get near. Doesn’t actually identify as cursed until it wakes something up.

None of these are intended to be immediately obvious. While they are like object properties, they don’t necessarily have to be implemented like those: the curse behavior of a weapon could be deterministically computed from its object id hash.