There is also the Greatsword of Atorias (cursed) which can be made with Sif's Soul.
This weapon is permanently cursed and always hurts ghosts.
Just watch out if you want to make this weapon at the Giant Blacksmith in Anor Londo. Because it has the same name as the normal Greatsword of Atorias. The only difference is, the normal Greatsword has magic damage while the cursed one does not.
[Edited by Kantenbauer, 9/13/2012 7:53:06 AM]
Thanks for the info!