In Le Morte D'Arthur, knights win acclaim and honor by proving themselves on the battlefield, and in tournaments and jousts. It's all about skill, and the knights who get the most praise are the talented ones, like Launcelot and Trystram. That is, until the "Tale of the Sankgreal." Suddenly, Arthur's knights are thrown into a world with a different values-system, in which religious practices like chastity, fasting, and prayer are more important than success on the battlefield. This puts knights like Launcelot out of their element since, as a good knight should, he's devoted himself to his lady and to bulking up for the next big battle. And there's yet one more skill that can trump knightly prowess: sorcery. At this, characters like Nenyve, Merlin, and Morgan le Fay excel, and with their skills are either a great help or a great thorn in the side of Arthur and his knights.
The "Tale of the Sankgreall" proves that in the end, skills in combat aren't worth all that much, so Camelot's value system needs to undergo a chance.
Arthur's gradual shift away from performing feats of arms to providing the opportunity for others to do so signals his transition from warlord to ruler.