Vincent’s Waterfall
In Disc 2, breed a gold chocobo and go to the waterfall in the centre of the western continent. I think you can get there with the submarine as well. Ride the Chocobo to the west of the waterfall where the grass is. Dismount and enter the waterfall. Go to the room with the white stone. You must have Vincent in your team. He will talk about Lucrecia. In Disc 3, return here(again with Vincent)and you will receive Vincent’s Ultimate Weapon, the Death Penalty, and his Level 4 Limit Break Manual, Chaos.