The Keyblade of People's Hearts, often referred to as the Dark Keyblade, is a Keyblade created by Xehanort's Heartless from the Hearts of the Princesses of Heart, sans Kairi. It is seen in only two cutscenes, one at either end of the single fight it is used in. It has yet to have any appearance beyond Kingdom Hearts. It has a simple design of red and black, akin to the Kingdom Key, with its teeth forming the outline of a heart. It has a rather dark design, despite being created from hearts of pure light.
Abilities
This Keyblade was created for the sole purpose of opening the Final Keyhole, by releasing Kairi's heart from within Sora. It contains the power to "unlock" the Darkness in people's Hearts, for most, resulting in a Heartless. It is unknown if it has the abilities of other Keyblades, such as locking and unlocking Keyholes.
As it is only used by Riku as a villain and Sora in a cutscene, its stats are unknown. It cannot be obtained or used.
Story
After Riku failed to defeat Sora and retain the Kingdom Key, Xehanort's Heartless possessed him. Through a process unknown, he then collected the six hearts he had gained to create the Keyblade of People's Hearts. It was first used to unlock Maleficent's darkness, and then to fight Sora. When Sora defeated Riku, he used the Keyblade of People's Hearts to unlock his own heart, releasing it alongside Kairi's. The Final Keyhole was opened, and the Keyblade then dissolved back into the six other hearts and returned to their respective Princesses.
With the release of the two hearts, both Roxas and Naminé were created.
The Keyblade of People's Hearts has yet to be seen again.
Speculation
This Keyblade is considered by most to be "artificial" due to its synthetic construction from hearts. Because of this, the weapon is not considered to a true Keyblade. It also lacks a keychain, possibly because it is artificial, or because it lacks the heart of the seventh princess.
However, as it is unknown what the true significance of keychains is and how other Keyblades are made.