In this section you will discover what each characters ultimate weapon is and where to find it, also any side notes that i have on using them.
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Cloud's ultimate weapon is, the Ultima Weapon. This Sword for Cloud does damage based on how high Cloud's HP is, so if you have full HP you'll hit very hard, however if you're near death you wont get much power into a hit at all. To get this you have to defeat Ultimate Weapon at the end of disc 2 or disc 3. For full instructions on finding and defeating Ultimate Weapon check my extras page
Aeris's ultimate weapon is unlike all the others in that it only has seven 0AP materia slots rather than eight, but oh well. Here's how you get the Princess Guard. When you get to the Temple of the Ancients, on the giant clock, enter door number IV (4) and you'll find it. Now, i can't be certain, but i believe that this weapon powers up when Aeris protects someone using cover materia, well, at least thats how it seems
Ok, now for Tifa's ultimate. It's called the Premium Heart and it's obtainable by, in disc 2/3, going to Bone Village and excavating the sector 5 gate key. Now go back to Midgar where you'll see a man walking about moaning that he's lost his key. Go up to the gate and it will open. Make your way to Wall Market and find the little shop that had a gun in it which would shoot at you if you pressed the button earlier in the game. now if you press the button you will be rewarded with Tifa's Premium Heart
Getting Barrett's ultimate weapon is dead easy. Missing Score can be gotten when you re-enter Midgar by parachute in disc 2. On the stairs before you fight Hojo is a chest containing the gun, be warned though, you must have Barrett in the party or it wont appear. This weapon powers up with the more AP it has on it, so put as much high level materia in it's slots and you're garunteed to be hitting at 9,999!
The Limited Moon is Red XIII's best weapon, and it's another easy one to get. In disc 3 go to Cosmo Canyon with Red in your party and Buganhagen will give it to him
To get Cid's Venus Gospel you have to wait until after you've finished the Huge Materia quest in Rocket Town. Simply talk to the old man outside of the Inn (he's the same guy who gave Cloud the Yoshiyuki earlier in the game)
The Conformer for Yuffie can be found once you've got the sub, in the downed Shinra plane, for details about the plane check the extras page. This weapon gets a boost depending on how strong the enemy you're fighting is, so if you're fighting Sephiroth it'll always attack at 9,999!
The HP Shout for Cait is found in the Shinra buling on floor 64 once you've parachuted back into Midgar (if you searched the locker with Cloud at the beginning of the game he notices it). When you get into the train system of Midgar you can get to the Shinra building
Vincent's ultimate weapon is the Death Penalty. You can find this in Lucresia's cave. check my extras page for more info. The Death Penalty does damage based on how many many enemies Vincent has killed, so make sure he's got a good tally