Vincent's Ultimate Weapon & Level 4 Limit Break

Vincent's ultimate weapon and Level 4 Limit Break can be found in the same place. When you have either a submarine or a Gold Chocobo, you can get them. With the Chocobo, go to the Nibelheim area and look for a crater completely surrounded by mountain. Go over the mountains to find a waterfall that flows into a lake. If you have the sub, look for an underwater canyon that will lead you straight through the western continent (the one with Nibelheim on it). At the dead end, surface to reach the crater. You can get out on the shore. PHS to put Vincent in your party, if he is not already in it. Now walk into the waterfall to enter a hidden cave. You will meet Lucrecia and learn a bit more about Vincent's past. Come back during Disk 3 with Vincent in your party to find Death Penalty, his ultimate weapon, and Chaos, his Level 4 Limit Break.