Chaos plagues the land. In the West, the King in Orange blusters and bloviates endlessly in barely comprehensible gibberish. Perhaps he is attempting to call forth the Elder Gods? In the East, the Queen of Mayflies glowers menacingly and shakes a vaguely pole-shaped object1 at friend, not foe. The people cry out for deliverance from this turmoil, and one man, the nominal head of an obscure anarcho-syndicalist commune in the countryside believes he has the answer.
The Lady of the Lake, her arm clad in the purest shimmering samite, held aloft Excalibur from the bosom of the water, signifying by divine providence that I, Arthur, was to carry Excalibur. That is why I am your king.
Waterytartocracy is the way forward, says he, the Lady of the Lake told him so. But who, or what, is this "Lady"?
She, or it, must:
Be able to live in a lake, or at least spend consecutive days underwater in said lake
Preserve one or more European swords of at least arming sword length in good condition underwater for extended periods of time
Possess one or more arms that can pass off as a human lady, preferably with the appearance of being clad in samite
From underwater, hear the sound of two empty coconut halves being banged together near the shoreline, so as to determine the Chosen One
Bonus points if she/it:
Actually looks like a human woman or mermaid, or at the very least has the silhouette of one while swimming when perceived from the shore
Can talk to humans, so as to participate in farcical aquatic ceremonies that confer supreme executive power
Breathe, move about, and otherwise function normally(for a human) on shore, also for the purposes of aforementioned ceremonies.
No actual magic is allowed.
1: Normally one might expect this to be a spear or scepter, but given the state of total confusion nobody knows what it actually is