Draw Your Weapon: Impossible Tasks as a Sign of Worth

Arthur becoming king in the Disney's The Sword in the Stone (1963)

Culhwch and Olwen follows the grand tradition of epic literature in which the hero, in order to achieve their goal, must perform a number of arbitrary (or seemingly so) tasks.

One of these tasks is to retrieve a set of grooming tools from their place on the head of 

Twrch Trwyth, an enormous boar. It occurs to me that one element we have yet to see in our examination of King Arthur is the famous "pull the sword out of the stone to become king" incident. Is this concept of the seemingly impossible task used to prove personal worth related?