Earthshaker

Unreleased Terra's Keyblade is a Keyblade used by Terra during his quest to find Master Xehanort.

Terra is shown summoning his Keyblade differently than how most wielders do.

Kingdom Hearts II Final Mix
The Lingering Sentiment uses this Keyblade to fight Sora after they save Disney Castle from the plunging darkness and so gives access to a wormhole in Kingdom Hearts II Final Mix.

During battle, the Lingering Sentiment can change the Keyblade into a whip, a jet-ski like object, a fast spinning cog-like weapon, and a massive cannon, among other formations, like making the Keyblade quadruple in size. It is unknown if Terra will have this ability in Kingdom Hearts Birth by Sleep, or if it only appears in the Lingering Sentiment's boss battle with Sora.

Kingdom Hearts Birth By Sleep
This particular Keyblade appears in the game as Terra's main and default weapon; it is unknown as of yet if he is able to currently equip other variations. The Keyblade in the game also hasn't yet shown the unique abilities it possessed during the battle against the Lingering Sentiment. Curiously, recent screenshots have shown a somewhat redesigned Keyblade with a keychain at the end of the hilt, where earlier images as well as the Lingering Sentiment's weapon lacked one.