By cheating.
you have to enter in ,eukbbekue
The Edge of Ultima is not a Keyblade that can be used in the actual game; it can only be obtained through cheating.
If you are asking this then you must be crazy because it is so easy but for those crazy people out there it is 4.
I've heard it was because he's an introvert that is always on the edge of social gatherings it was also a joke among the band that it was a joke about his oddly shaped head.