This version of King Arthur changes King Arthur's ability to allow for him to use his health as a resource as well as giving some more consistency to his deck and some added value to Merlin's schemes. The fantasy here is that King Arthur's attacks are still telegraphed and punishable, but he can grit his teeth and push through damage in order to swing again.
It allows for King Arthur to be more aggressive and quicker, because it also removes his ability to stall the game with the addition of "Gain an action" to many of his cards that originally could be used as "passes" (turns that do not require him to draw, thus allowing him to pressure the opponent's exhaustion state.)
A weakness of this variant is simply how much it changes. It requires a player to partially relearn the character and matchup, which for some tables will be a non-starter.
Creates a decision point instead of a binary. Allows for player expression and game state to dictate what's "optimal."
"Gain an action" added to allow for better maneuverability against ranged opponents or defensive. Forces King Arthur to be aggressive because if pushes him toward exhaustion.
Functions almost identically to having a second EXCALIBUR in deck without losing the flavor of having the LADY. "Gain an action" also forces aggression.
TwisterStrudel playing the variant in his YT series.