I forgot to post this between the ending of part 3 and Le Morte d'Merlin. Sorry for any confusion. Hope you like this!
Arthur had just met the Freya, or the Lady of the Lake, as he knew her as. He stood on the bank, admiring Excalibur.
"So why did you put this amazing sword in the lake?" He eventually asked Merlin after inspecting it.
"Funny story actually. Well, I had the sword and I wasn't allowed to give it to you because of a promise to the dr—somebody. So I had to take it to this lake until you could come get it. This was again because of that promise to somebody.
"You really are the Camelot's biggest idiot aren't you?"