The first ultimate weapon to look at in “Final Fantasy VII” is that of Aerith. Her ultimate weapon is quite different, as it is much weaker and obtained much earlier on in the game than every other ultimate weapon to be had. Known as the “Wedding Guard”, Aerith's ultimate weapon can be found within a room located at the Temple of the Ancients.
Just as with every other ultimate weapon, Aerith's gives no Materia growth, however it does provide 7 Materia slots. While weaker than any other ultimate weapon, the Wedding Guard has quite the stipulation to make up for that. If one ally is dead in battle, then the weapon's damage is doubled. In the same respect, if both allies are dead and Aerith is the last one standing, the weapon's power is tripled.
The second ultimate weapon, and perhaps the most common one to get in a playthrough, is Cloud's Ultima Weapon, a sword that has a small blue center surrounded by a transparent white blade on either side.
The weapon is obtained late in the second disk via defeating Ultimate Weapon, who can initially be found hovering over a lake near Junon, and will begin to fly around the world until having a final battle with the party over Cosmo Canyon. Upon defeating him here, the player will get the Ultima Weapon for Cloud as a drop from the boss.
This weapon has eight Materia slots, and a very interesting ability. Essentially, when used in battle, the more HP Cloud has, the more damage Ultima Weapon will deal. An interesting feature of this weapon is that when Cloud's HP drops, the transparent white edges of the sword begin to turn more blue, ultimately becoming an extremely dark blue color when Cloud is on his lowest amount of HP.