Why did king arthur want to throw excalibur back to the lady of the lake?
There are many speculations as to why Arthur would return Excalibur to the Lady of the Lake, even assuming the story is true. The most likely reason was that Arthur was nearing the end of his reign. If I remember one version of the story, another knight after the battle of Camlann (where Arthur is mortally wounded) is given the task of returning the sword to the Lady of the Lake. This implies that the sword does not belong to Arthur so much as it does to the land itself, in the persona of the Lady of the Lake. Since she is the one who bequeathed the sword, the sword can be considered rightfully returned to her at the end of its service to Arthur. Returning the sword also means that the Lady of the Lake will take trust of the sword until Arthur (or someone of his stature) requires it again. If you want to protect a magickal artifact, hiding it with a magickal being makes perfect sense. The second reason would be the most obvious: a powerful artifact can create a strong desire to wield i