Blade Brothers

The Blade Brothers are characters in. They are self-trained swordsmen, and have each won the fighting tournament at the Picori Festival. If Link trains with them, they will grant him various techniques for his sword, generally in the form of Tiger Scrolls. Each brother resides within his own "Dojo", although Swiftblade's is the only one that is actually a building—the other brothers reside within caves, graves, and even hollowed-out trees. Each of the brothers who award Link with Tiger Scrolls use the Possession Technique, which allows them to control Link's body and demonstrate the technique. The other three brothers instead use "visualization training," and tell Link to focus on his sword performing more ably.

Although Link must visit Swiftblade and learn the Spin Attack in order to complete the game, the other brothers are completely optional. Link can sometimes train with a brother as soon as he finds them, but they usually require him to have achieved a certain accomplishment before they will teach him. Furthermore, the three brothers who upgrade Link's previously-learned techniques can only be found after fusing Kinstones with the other brothers.

Swiftblade
Swiftblade is the second eldest of the Blade Brothers. His dojo is a building in the southwest corner of the town. Unlike the other brothers, he teaches four separate techniques—the Spin Attack, Dash Attack, Rock Breaker, and Down Thrust. In order to learn the latter three techniques, Link must obtain the White Sword, Pegasus Boots, and Roc's Cape, respectively.

After Link fuses Kinstones with the Postman, Swiftblade will also start writing the Swordsman Newsletter.

In, Link attends classes at Swiftblade's dojo for a while, but during the registration for the fighting tournament, Swiftblade gruffly tells Link that he is not ready to enter.

Grayblade
Grayblade lives in a cave on the eastern side of Mount Crenel. He teaches the Roll Attack. His dojo can only be entered once Link can split into two using the White Sword.

Link can fuse Kinstones with Grayblade to reveal Scarblade's dojo.

Waveblade
Waveblade lives under a tree on the southwest side of Lake Hylia. He teaches the Peril Beam. His dojo can only be accessed once Link can swim to it using the Flippers. Waveblade will not train Link unless he has more than ten hearts.

Link can fuse Kinstones with Waveblade to reveal Greatblade's dojo.

Grimblade
Grimblade lives in a cave on southeast side of the Hyrule Castle Garden. He teaches the Sword Beam. Grimblade will not train Link unless he lights the torches in the room with the Flame Lantern.

Link can fuse Kinstones with Grimblade to reveal Splitblade's dojo.

Scarblade
Scarblade lives in a waterfall cave on the northeast side of Castor Wilds. He will teach Link to release his Spin Attack quicker. His dojo can only be accessed once Link fuses Kinstones with Grayblade and can swim to it using the Flippers.

Splitblade
Splitblade lives in a waterfall cave on the southern side of Veil Falls. He will teach Link to charge his Split Gauge faster. His dojo can only be accessed once Link fuses Kinstones with Grimblade and can swim to it using the Flippers.

Greatblade
Greatblade lives in a waterfall cave on the western side of North Hyrule Field. He will teach Link to prolong the duration of his Great Spin Attack. His dojo can only be accessed once Link fuses Kinstones with Waveblade and can swim to it using the Flippers. Greatblade will not train Link until he obtains the Great Spin Attack from Swiftblade I.

Swiftblade I
Swiftblade I is the eldest of the Blade Brothers, and "lives" under his grave on the southwest side of Castor Wilds. He teaches the Great Spin Attack, which he claims only he has mastered. His dojo can only be accessed once Link can dash to it using the Pegasus Boots. Swiftblade I will not train Link until he obtains the first seven Tiger Scrolls.

Trivia

 * Although both the figurine and the game only feature eight Blade Brothers, Swiftblade claims in the Swordsman Newsletter that, "There are nine of us, not counting the ghost of Swiftblade the First."

Theories
Some fans believe that the Hero of Men who appears in the stained glass in is in fact Swiftblade the First.