Some of these weapons are tough to find, and most of them can only be found during Disc 3. Sometimes there are side quests to complete in order to get them as well. All of these weapons have 8 linked slots of materia available but the growth rate is 0, so you will never get any AP while these are equipped.
Cloud - The Ultima Weapon
Cloud's ultimate weapon, the "Ultima Weapon", can be found by defeating the Ultimate Weapon in Disc 3. Fly around with the Highwind and bump into the Ultimate Weapon to initiate a battle against him.
Tifa - Premium Heart
This can be found in Midgar in Disc 2. Go back to Midgar, to the same slums wher Don Corneo's Mansion is. In a house house you'll find a computer with a machine-gun that has it
Barret - Missing Score
This can be found on the staircase right before Hojo during hte raid of Midgar. Barret must be in your party for the item to be on the staircase.
Aeris - Princess Guard
When going through the Ancient's Temple towards the end of Disc 1 you will be taken to a room where you have to move a number of giant clock hands. Move the hands so you are able to walk over to IIII and enter the room to get it.
Red XIII - Limited Moon
After the WEAPONs attack Midgar in Disc 2, return to Bugenhagen in his observatory in Cosmo Canyon to get it.
Cait Sith - Marvelous Cheer
If you return to Shinra HQ that had the exercise equipment and the lockers during the raid of Midgar on Disc 2, the Marvelous Cheer can be found in one of the lockers that was locked the first time through.
Yuffie - Conformer
Yuffie's Conformer can be found in the Sunken Gelnika.
Cid - Venus Gospel
Talk to this old man in Rocket Town 3 times and he will give it to you.
Vincent - Death Penalty
Found in Lucrecia's Cave in Disc 3.
