Master Sword

From Zelda - Wiki on Neoseeker

As seen in Wind Waker

The Master sword is the pinnacle of all Zelda weapons, it is often omitted from more minor Zelda games, but is usually the strongest weapon available in all those it appears in.

It normally appears after you have gone through the first set of dungeons (Usually 3), no other weapon is like it and if you pay careful attention you will notice that it will do more heart damage to regular creatures than your previous sword.

In most places it is found in the sacred realm or the area that was built upon it (Temple of Time in Ocarina of Time) or the most recent exception, the sacred grove in Twilight Princess, However, the grove was confirmed to be a decaying Temple of Time.

The Sword is of Majora Plot significance, its only minor role being in Twilight Princess where, like Zelda herself, it seemed forced in.

History

When Din, Nayru and Farore had created the world they had left behind an ultimate power known as the Triforce. If one were to so much as touch it, they would be granted their ultimate wish. The godesses had forseen this and created two ways of countering the effect. If someone were to touch the triforce and hold one of its two elements more dear than the others the Triforce would shatter, each piece residing in those whose hearts truly do rest in Wisdom, Courage and Power. But even that wasn't enough, the Goddesses knew that just one piece of the Triforce would be enough to take over the world, so they created one last thing. The Master Sword.

The Sword was designed so that only one with a pure heart could draw the blade. However the sword couldn't kill the Wielder of the Triforce (or at least the Triforce of Power) only seal him away within a sacred world. But it alone can't retain this power. In order to do so first the Seven Sages had to be called. This was the first instance of its power being granted. In one timeline its power began to subside, because the two Sages who had been keeping the Sword's power had been vanquished.

In another timeline, the Young, the Sword had technically never been given its powers, thus the Sealing of Ganondorf has always been different. However the Young Timeline is much more complex than the Adult Timeline, making it hard to pinpoint exactly what order it went in.