Four Sword

The Four Sword is used by the Link, in the The Legend of Zelda: The Minish Cap, The Legend of Zelda: Four Swords, and The Legend of Zelda: Four Swords Adventures. It has a long, strange history, starting with the story of the Minish Cap.

The Minish Cap
There is a large fair and sword contest thrown every year in Hyrule to honor the little people called the Picori by the Hylians (the Picori call themselves Minish). The winner of the sword contest gets to touch the magical Picori Sword, gifted to the Hylians by the Picori themselves. Link, the grandson of the Royal Grand Blacksmith, and the Princess of Hyrule, Zelda, are watching the contest when a strange swordsman named Vaati wins the contest. When he goes up to touch the Picori Sword, he breaks it off at the hilt. Then, he turns Zelda into stone and escapes. The king sends Link to seek out the Picori because they are said to show themselves only to children.

Link eventually finds a green cap with a bird head named Ezlo. Ezlo allows Link to shrink down and speak with the Minish. It is later revealed that Ezlo was once a skilled Minish craftsman, Vaati, his apprentice, used a magical cap created by Elzo to turn into a powerful sorceror. He turned Ezlo into the Minish Cap. Link eventually gets the Picori Sword fixed. The new blade is called the White Sword. Then, when Link embues the sword with the powers of the four elementals, it is transformed to a more powerful sword, called the Four Sword.

Vaati, who transformed himself into a demon, was sealed in the Four Sword when Link defeated him, and the sword was sealed in the Altar and Princess Zelda was revived. The three goddesses then put a spell on the sword that makes the wielder split into four versions of himself.

Four Swords
Zelda and the Seven Maidens sense a disturbance in the Four Sword, and Link pulls it again. Vaati is released again. The four Links defeat Vaati once again and put the Four Sword back in the Seal. For now, this is the end of the adventures of the Four Sword.

Four Swords Adventures
Many years later, the seven maidens are trapped by Ganon with help from a mysterious clone of Link, known as Shadow Link. When Link pulled the Four Sword from the pedestal, Vaati was released again. This time, the four Links saved the seven maidens, defeated Vaati, and were escaping from the tower when they encountered none other than Ganon, whose power has been restored to him by the Trident. The four Links defeated Ganon and their story became a myth. Every time one of the Links collects over 2,000 force gems, the Four Sword powered up, turning into the Ultimate Four Sword.

Four Sword in manga
Seemed to follow most of the game's plot. However it not splits its wielder into four, but divides the wielder's personality aspects into the four beings as well with one of them possessing a persona similar to that of their original state.