Merlin stares without blinking at the Devourer after he asks me the question. I can only say that he is someone who has indeed aided the late King Arthur to even detect the power of the real Excalibur inside the Devourer though that is natural since it is Merlin himself who knows the real power of the sword and how it was a sword that is prophesized to choose the next king. If only the king himself was a good one then nothing bad should happen.
And since Merlin also wields a replica of the Excalibur, it is safe to assume that he knows the real sword as well. Lying is not going to help me in this matter anyway so telling him the truth would be much better.
"I was tasked to retrieve the Excalibur here in Agartha to aid me in defeating the Goddess of Life. I found it not too far from the entrance of Agartha and extracted it there. Of course, after the task is done, I will be returning the weapon to where I found it."