There is no absolute way of knowing, but we are forced to believe that his weapon of choice is the Kingdom Key. Sora is seen with the Kingdom Key in almost all main clips and cutscenes, regardless of what Keyblade the user has equipped before the clip plays.
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IMPROVED ANSWER
i dont really know this but roxas uses thr oathkeeper and oblivion keyblades.
Yes, Sora is a chosen keyblade master. He is the main Keyblade wielder, the second being King Mickey. Sora was chosen to be the keyblade master because of his powerful heart and strength. SPOILER****************** Terra wanted Riku to be the keyblade master, but Sora's heart was more powerful, thus Sora was able to combine his heart with Ven, allowing him to wield any keyblade.
Because his heart is strong and pure!^_^The keyblade originally chose Riku and Sora was supposed deliver it to him, but Riku's weak heart gave into darkness, so the keyblade chose Sora as its master.
They don't need to be. They're with Sora, who does have the keyblade. Anyone with Sora is capable of releasing the hearts and the keyblade absorbs them, or sends them to where they need to be. This is sort of explained in 358/2, with Xion losing her ability to wield the keyblade, so she teams up with Roxas, who can.
well technically, Sora's Keyblade is Rikus, as Terra chose Riku, not Sora. Sora was given it as Riku gave into the Darkness. The reason his sword became a Keyblade is as he was no longer evil and could now wield a keyblade
... do you mean Xion? If so, Xion isn't Kairi's nobody, Namine is. Xion is simply the result of an experiment in Castle Oblivion on Sora; she's an "imperfect replica of Sora". That's why she's able to wield the keyblade
Unless you have a game modification system such as an Action Replay or GameShark, this is not possible. Sora must be in a drive form to wield more than one keyblade at once.
The Keyblade chose Sora in Destiny Islands. Sora's first Keyblade was the Kingdom Key, but it changed into different versions, like Hidden Dragon, Circle Of Life, etc.
The Keyblade chose Sora because he has a strong heart and would do anything for his friends.
Because it was his understanding that Sora and Riku were the only wielders of the Keyblade.
The strongest keyblade (in terms of attack power) is the Fenrir Keyblade.
Sora CAN in fact give the keyblade to someone else, but that doesn't guarantee that it will work for them. Plus, it always returns to Sora because he is the destined wielder of the keyblade.
Sora's first keyblade is 'The Kingdom Key'. This is the most common keyblade used in cutscenes throughout the game and is the most recognizable keyblade.