I mean, that was pretty much expected. It was already crazy he blew right through training, selection, ranking up, and into the royal guard just from one match the Princess saw. If he also spanked the Captain of the Royal Guard on top of that, it'd just be silly. Now he has a point of strength reference to strive towards.
Still gotta hand it to him though, he held out pretty good against him for somebody that only really practiced swordsmanship in a random country village with no formal training. You can't say he used his pilfered skills to seem better than he is.