SPOILERS
So the X Blade is a counter part to Kingdom Hearts and its purpose is to defend it. Which makes me believe that there must have been a wielder who used the x blade. Would it make sense for the x blade to just defend Kingdom Hearts itself? I'm guessing that in the world of chi the MoM is in possession of the blade and its most likely in that suspicious looking box. The x-blade was said to split into fragments after the key blade war so someone is in possession of the x blade. Also, all other keyblades were formed in the image of the x blade so people must have been aware of what it looks like. If Luxu's keyblade is the most ancient then is it possible that he was the Master's first apprentice and the master created it for him based on the x blade? Just a theory...
So the X Blade is a counter part to Kingdom Hearts and its purpose is to defend it. Which makes me believe that there must have been a wielder who used the x blade. Would it make sense for the x blade to just defend Kingdom Hearts itself? I'm guessing that in the world of chi the MoM is in possession of the blade and its most likely in that suspicious looking box. The x-blade was said to split into fragments after the key blade war so someone is in possession of the x blade. Also, all other keyblades were formed in the image of the x blade so people must have been aware of what it looks like. If Luxu's keyblade is the most ancient then is it possible that he was the Master's first apprentice and the master created it for him based on the x blade? Just a theory...