Keyblade

The Keyblades (キーブレード) are mysterious weapons that are heavily featured in the Kingdom Hearts series. Wielded by the main character, Sora, as well as a number of other important characters, the Keyblade is a main part of the battle between Darkness and Light.

Powers
As the name implies, in combat, Keyblades are used in a manner similar to swords. Despite the fact that most possess no actual blade, Keyblades still make efficient combat weapons and are shown to be particularly effective weapons against both Heartless and Nobodies. Keyblades vary in appearance, possibly to represent the realm they came from.

The main power of the Keyblade, however, is the ability to seal or open the barriers between worlds, as well as "lock" a world's Keyhole, preventing the Heartless from attacking that world's heart. As an offset of this ability, the Keyblade can also be used to lock or unlock any lock, allowing the user to access any sealed interior, whether it be a locked room, gate or treasure chest.

In addition to its base powers, it is possible to modify a Keyblade's appearance and powers by attaching various Keychains or Gears in the wielder's inventory. There are other instances of the Keyblade changing form, such as when Riku's Soul Eater becomes the Way to the Dawn and when Roxas's two Kingdom Keys transmute into the Oathkeeper and Oblivion, but the mechanism behind these transformations is uncertain.

While there are many qualities a Keyblade wielder must have, the only known requirement is that they have an exceptionally strong heart. However, there are two exceptions to even this rule: Roxas, Sora's Nobody, who is able to wield Keyblades because Sora can, and Xion, an imperfect clone of Sora created from his leaked memories, who wields Keyblades for the same reason.

Magic
Keyblades are natural conduits for casting magic, as seen when Sora uses his Keyblade to command his magical attacks. Some Keyblades have the innate ability to enhance specific kinds of magic, and many also augment the user's magical abilities on a more general level. Keyblades can also augment the holder with other powers and abilities that they would not normally be able to use.

Dual Wielding
Keyblade wielders are also able to generate a second Keyblade using the Synch Blade ability. After Roxas defeats Xion and absorbs her, he uses this ability at all times, generally with the Oathkeeper and Oblivion keychains, while Sora only uses this ability while in his Valor, Master, or Final Drive Forms. Riku also exhibits this ability when he and Kairi meet up at The Castle that Never Was, and he hands the second Keyblade to Kairi to allow her to help protect Sora.

Keyblade wielders are also able to allow others to wield this second Keyblade, or have it taken by the other wielder. When Roxas encounters Riku at Memory's Skyscraper he throws his Oblivion at Riku. Riku catches it and actually wields it in battle against him; when Roxas and Sora fight within Sora's heart, Sora is able to steal Roxas's Keyblades to use against him.

Appearance
All Keyblades shown have the same distinguishing features that are modeled after a key: a guard with a handle, a hilt and a head at the end of the shaft that resembles the teeth of a skeleton key (with the exception of Fenrir, which is instead modeled after a pin tumbler lock key). All Keyblades also have some theme, usually a World or a person associated with that World, that will reflect in its appearance.

Seen below are the Keyblades main character Sora has used throughout Kingdom Hearts and Kingdom Hearts II, via attaching keychains from various worlds and people to alter his main blade's appearance.

History
The origins of the Keyblades is, thus far, unclear. Each game references the special qualities of the wielders and some give vague explanations of the Keyblades' power, but none have shown where the Keyblades originated, how they are created, or what their original purpose might have been. One legend mentioned in Kingdom Hearts states that the Keyblade master saved the world, while another said he wrought chaos and destruction upon it. While these legends may appear to contradict themselves, it can be assumed that the Keyblade master chooses how to use the Keyblade, whether for good or evil. The Keyblade is known throughout the worlds as a unique and powerful weapon. In Atlantica, King Triton and Ursula both knew of the Keyblade and its powers. King Triton did not want Sora to seal the Keyhole because he thought that the Keyblade would send his world into chaos, while Ursula knew that it gave the ability for the one who wields it to travel around the worlds.

One of the pieces of text in the hidden ending video for Kingdom Hearts II, "the Gathering", mentions a "Keyblade War". Hundreds of Keyblades can be seen stuck into the ground during this cinematic, as well as the extended "Birth By Sleep" cinematic at the end of Final Mix+. It should be noted that none of these seemingly abandoned Keyblades, nor those of protagonists Aqua, Terra or Ven, have keychains, although the significance of this detail is currently unknown as the history of the Keyblades is unknown. Many of these Keyblades seem to be based on Keyblades already shown in the series, but many more are entirely original and new.

Theories About Keychains
There are many theories surrounding the Keyblade that include what a Keyblade's purpose is, how a Keyblade is formed, and the significance of a keychain.

One theory speculates that when one creates a Keyblade, as Xehanort's Heartless did by the use of Riku, there is no keychain with it. That would indicate that the Keyblade can then be created either by the person or from the person. Examples would include Xehanort's Keyblade, which was created from the Princesses of Heart and Riku's Keyblade, which was created from the Soul Eater, which was forged out of his own darkness. The Keyblade can then be seen as an extension of its creator. A Keyblade's power comes from its creator alone. Therefore, when a Keyblade needs to be passed to a person, a keychain is formed to be a power source to give the Keyblade lasting energy as well as its power and form. This could possibly explain why some Keyblades do not have keychains such as Terra, Ven and Aqua's Keyblades. It could also show how Riku got his Keyblade, Way to the Dawn, as well. This would suggest that each Keyblade has its own unique power and form. This could explain why the moogles are able to synthesize the Ultima Weapon.

Yet, another theory would be that the Keychain is a physical embodiment of one's memories. This would explain why Sora got new Keyblades for every world, as well as why he is able to receive them as gifts from friends (eg. Oathkeeper, Gullwing). It also explains Roxas's Keyblades; because Roxas is Sora's Nobody, Roxas's Oblivion represents Sora's memory of Riku while his Oathkeeper represents Sora's memory of Kairi.

Another theory would be that Keyblades without Keychains are merely "apprentice" Keyblades. This would explain why Terra, Aqua and Ven's Keyblades do not possess Keychains, while Master Xehanort's and the "Dark Soldier's" Keyblades do.

Some fans believe that the Keyblade or its creator is the mysterious voice, which guides Sora and Roxas in the beginning and ending of both games.

It has been rumored that without the keychains, the Keyblade might not have much effect. However, Terra, Aqua, and Ven do not have keychains at the end of their Keyblades. Also, the keychains just change the form and give it different stats, therefore making the rumor highly illogical.

Another theory about keychains is that the keychain grants access to other Keyblade wielders. If a Keyblade has no keychain, then it is only exclusive only to its wielder, and cannot be given to another Chosen Keyblade Wielder. This theory could potentially explain why the countless, keychainless Keyblades at Sunset Horizon are not in use. However, in the battle against Xemnas, after Riku takes the finishing blow for Sora, it is shown that Riku passes his keyblade (with no keychain) to Sora as he falls, giving Sora the opportunity to bombard Xemnas with a flurry of attacks. Keyblades without keychains cannot be axclusive, then. Also the Dark Keyblade Riku makes when possesed by Xehenort's Heartless (with no keychain) was picked up by Sora which he used on himself, not exclusive.

Keyblade Wielders
For a complete list, see: List of Known Keyblade Wielders

Sora
The most prominent character in the series to use a Keyblade is Sora, who has used them successfully in the two main games in the series(with one minor incident). His ability to use and possess the Keyblade was a major plot point in the first game. He has used more Keyblades than anyone else in the Kingdom Hearts series; the variations are created through various keychains attached to his original blade, the Kingdom Key.

King Mickey
The King of Disney Castle, King Mickey's Keyblade is known as "Kingdom Key D". It looks the same as Kingdom Key, but its colors are inverted compared to the Kingdom Key.

Riku
Sora's best friend and rival, he wields the Way to the Dawn Keyblade. In Kingdom Hearts, he stayed behind with King Mickey in the Realm of Darkness. In Kingdom Hearts: Chain of Memories, he explores the basement of Castle Oblivion and struggles in resisting the darkness in his heart, Xehanort's Heartless. while in the second game, he helped Sora defeat Xemnas. In Kingdom Hearts: Chain of Memories and Kingdom Hearts, he used the Soul Eater as his main weapon until he received the Way to the Dawn Keyblade.

Trivia

 * The negative space in the teeth of the Kingdom Key is identical to the necklace that Sora wears and the keychain on Oblivion.


 * Likewise, the negative space in Riku's Dark Keyblade resembles a heart.


 * It is unknown if Sora still possess his other Keyblades from Kingdom Hearts in Kingdom Hearts II. Most likely, he doesn't possess them because of the time spent in Castle Oblivion, although Sora still had the keychains for Oathkeeper and Oblivion. However, it could be argued that both keychains returned in Kingdom Hearts II because both are fan favorites, and both represent Sora's friendship with Kairi and Riku respectively. Also, Oathkeeper had to return due to Sora's promise to Kairi that he would return to her with Riku.


 * Fans argue whether the Dark Keyblade was a true keyblade, those in favor basing their opinions on speculated theories. However, when Sora talks with Leon at Traverse Town after his first trip to Hollow Bastion, Leon explains that the Dark Keyblade was not a true Keyblade, as it was forged out of six of the seven princesses of heart's hearts, and, like Hollow Bastion's keyhole, would remain incomplete without the heart of the seventh princess, Kairi. Since Sora's use of the Dark Keyblade was a heroic sacrifice, instead of a malicious intention of use, the Dark Keyblade unraveled back to the six hearts of the princesses, which returned to their bodies.


 * When the Keyblade is either used to lock a Keyhole or open a new path, it shoots a small, but bright beam of light. Sora has been shown in cutscenes, an example being Ursula's Revenge, to use this as an attack, though it can not be used in actual gameplay.

Keyblade