Sapphire Weapon

Overview

Sapphire Weapon is one of five WEAPONs created by the planet Gaia to protect itself against various types of threats, most prominently JENOVA.  Sapphire Weapon is the first weapon to reappear after the planet had awoken them at the Northen Crater, and is the only WEAPON that is never fought by the player as a boss.

Final Fantasy VII

Sapphire Weapon appears in the ocean off the coast of Junon Harbor, a week after the WEAPONs have been awoken by the planet.  Sapphire Weapon appears at an opportune time, as it attacks Junon Harbor with a super heated plasma beam from its mouth, which coincidentally allows Tifa to escape her execution chamber.

Shortly after its attack, Rufus orders the Sister Ray mako cannon to be fired just as Sapphire Weapon is about to attack again.  However, Sapphire Weapon is positioned directly in front of the Sister Ray and promptly takes a giant blast of compressed mako energy in the face.  Sapphire Weapon's head explodes, and it then sinks to the bottom of the ocean.

Trivia

Many fans have speculated that Sapphire Weapon is in actuality Emerald Weapon.  This is due to the fact that Emerald Weapon appears to have no head, and is found swimming under the ocean surface near Junon Habor, exactly where Sapphire Weapon was destroyed.  This has been proven false however, due to their significantly different designs, as well as the fact that five WEAPONs can be seen leaving the North Crater when they are awoken by Gaia.  Most importantly however, is that Sapphire Weapon has been given its own name by the creators and it has been stated as such that they are not the same WEAPON.  The confusion by fans had mostly arisen simply due to Sapphire Weapon never being mentioned by name in the game, as it was always addressed to as WEAPON during all of its appearances throughout the Junon Harbor attack sequence.