Do We Celebrate the Death of A Wicked Person

There’s been a lot of debate around out house lately if it’s proper to throw a party in celebration of the death of the arch-terrorist Arafat. My sister feels that the death of someone who’s killed so many Jews deserves a major bash. I don’t have a good reason to argue with her, but deep down feel there’s something Jewishly wrong with doing that. What can you say about this?