The Ends of the Earth (ガイアベイン Gaia Bein?, lit. "Gaia Bane") is a Keychain for Terra's Keyblade that is found in Kingdom Hearts II Final Mix, Kingdom Hearts Birth by Sleep, and Kingdom Hearts Birth by Sleep Final Mix.
Like Terra's other Keyblades, it is able to shift into multiple forms, including a whip, a jet-vehicle, a spinning-cog weapon, a cannon, and a gigantic Keyblade.
In Kingdom Hearts Birth by Sleep, Terra's Keyblade develops this form after he chooses Riku to inherit the Keyblade. Terra's Keyblade permanently takes this form once his body is stolen by Master Xehanort, and his armor becomes the Lingering Will.
The Lingering Will continues to use this Keyblade, even when it attacks Sora in Kingdom Hearts II Final Mix.
In Kingdom Hearts Birth by Sleep, the Ends of the Earth retains its Keychain, but in Kingdom Hearts II Final Mix, it has been removed.
The Keychain had not been designed by the time the Kingdom Hearts II Final Mix was released. Being an upgraded version of the Earthshaker, the Ends of the Earth features a longer and more extravagant blade with teeth on both sides at the tip of the blade.
The hand guard also elongates to form a wing-like shape of sorts. The Keychain is a rock fragment similar to the one on the Earthshaker. In Kingdom Hearts Birth by Sleep, the blade's length appears to have been slightly decreased, and the spacing between the teeth of the blade is more narrow. The teeth themselves seem to be wider.
"Ends" can refer to the death or result of something, while "earth" refers to the Latin meaning of Terra's own name. "Bane" is a source of misery. Gaia is a deity in Greek mythology representing the Earth and the mother of the Titans.
Her Roman equivalent was named "Terra" or "Tellus". "Gaia" is also a recurring term in the Final Fantasy series. The term "Ends of the Earth" is also a common colloquialism for extreme effort or will, possibly symbolizing the powerful will that Terra possesses.