Marion Zimmer Bradley, From Mists of Avalon: Grounds for Arthur Accepting Excalibur

“Come,” Viviane said, and leading the way—The Lady of Avalon, in her own place, preceded even a king—she passed from the house and along the shores of the Lake and into the building where the priests were housed. Arthur walked quietly at Morgaine’s side, and for an instant she half expected him to reach out his hand as he had done when he was very little, clinging to hers…but now that little hand she had held was a warrior’s hand, bigger than her own, hardened with long practice at sword play and with other weapons. Behind Arthur and Morgaine came the Merlin, and at his side Kevin.
Down a narrow flight of steps they went, and the dank smell of underground surrounded them. Morgaine did not see anyone strike a light, but suddenly there was a tiny glow in the darkness and a plae light flared around them. Viviane stopped, so abruptly that they jostled into her, and for an instant Morgaine was surprised that she felt simply soft and small, an ordinary woman’s body, not a remote image of the Goddess. The Lady reached out and took Arthur’s wrist in her small dark hand; it did not come near to reaching around his.
“Arthur, son of Igraine of Avalon and of Pendragon, rightful King of all Britain,” she said, “behold the most sacred things in all your land.”
The light flared on gold and jewels in cup and platter, the long spear, the crimson and gold and silver threads of the scabbard. And from the scabbard, Viviane drew forth the long, dark blade. Dimly, stones glinted in its hilt.
“The sword of the Sacred Regalia of the Druids,” she said quietly. “Swear now to me, Arthur Pendragon, King of Britain, that when you come to your crown, you will deal fairly with Druid as with Christian, and that you will be guided by the sacred magic of those who have set you on this throne.”
Arthur reached for the sword, his eyes wide; Morgaine could see it in his eyes—that he knew what manner of sword this was. Viviane made a quick gesture, preventing him.
“It is death to touch the holy things unprepared,” she said. “Arthur, swear. With this sword in your hand, there is no chieftain or king, pagan or Christian, who will stand against you. But this is no sword for a king who is bound to hear only the Christian priests. If you will not swear, you may depart now, bearing such weapons as you can get from your Christian followers, and the folk who look to Avalon for their rule shall follow you only when we bid them to do so. Or will you swear, and have their allegiance through the sacred weapons of Avalon? Choose, Arthur.”
He stared at her, frowning a little, the pale light glinting on his hair, which looked almost white. He said, “There can be only one ruler in this land; I must not be ruled from Avalon.”
“Nor must you be ruled by the priests who would make you a pawn of their dead God,” said Viviane quietly. “But we will not urge you. Choose whether or no you will take this sword, or refuse it and rule in your own name, despising the help of the Old Gods.”
Morgaine saw that strike home—the day when he had run among the deer and the Old Gods had given him victory, so that he was acclaimed king among these people, the first to acclaim him. He said quickly, “God forbid I should despise—“ and stopped, swallowing hard. “What must I swear, Lady?”
“Only this: to deal fairlyly with all men, whether or no they follow the God of the Christians, and always to reverence the Gods of Avalon. For whatever the Christians say, Arthur Pendragon, and whatever they may call their God, all the Gods are as one God, and all the Goddesses but one Goddess. Swear only to be true to that truth, and not to cling to one and despise another.”
“You have seen, said the Merlin, his voice deep and resonant in the silence, “that I do truly reverence the Christ and that I have knelt at the altar and shared their sacred meal.”
Arthur said, troubled, “Why that’s true, my lord Merlin. And you, I think, are the councilor I shall trust more than any other. Do you bid me swear, then?”
“My lord and king,” said the Merlin, “you are young for this rule and perhaps your priests and bishops would presume to keep the conscience even of a king. But I am not a priest; I am a Druid. And I say only that wisdom and truth are not the special property of any priest. Ask your own conscience, Arthur, if it would be wrong to swear to deal fairly with all men and whatever Gods they worship, instead of swearing allegiance to one only.”
Arthur said quietly, “Well then, I will swear, and take the sword.”
“Kneel, then,” Viviane said, “in token that a king is but a man, and a priestess, even a high priestess, no more than a woman, but that the Gods are over us all.”