User blog comment:AverageSchizoid/Buffs and Souls/@comment-98.118.183.215-20130123225655

I agree, Boss Weapons are situational. The Greatsword of Artorias is made for New Londo, as the cursed version allows smacks to be traded with ghosts and the uncursed version does more damage to Darkwraithes and I believe the Four Kings, but I'm not sure. Boss weapons also have different affects, such as a projectile or the Space Program (launches enemies.)