Let's keep Asta as the MC, and start from the beginning, let's give asta a special non-magic ability of instinctively get a basic understanding of how to use any weapon he touches.

Just how to use it/how it works. No Mastering it Automatically.

This makes his 6 month training after the Chain Guy incident a lot more worthwhile.

Let's just say he figures out how to use Sword Flight, since he has a basic understanding and no other techniques to focus on.

Except that Fanfiction made canon story of Asta learning Swordsmanship.

Most of the Magic Knights Exam happen as canon, then in the Broom Flight Round, Asta uses his sword to fly and probably even races Yuno, shocking everyone with his flight and control ability as he ties with Yuno in his unofficial contest.

Other contestants are a lot more wary of Asta now. So, Yuno is able to challange Asta first.

Then, their fight is pretty close, showing off his anti magic and magic reflection qualities and Yuno's genius. After 30 mins or so of battle Yuno Wins, because Asta doesn't have more stamina.

In the End, Many captains raise their hands.

Golden Dawn( Because of elf), Crimson Lion because fugoleon can see his potential, Black Bulls because Yami is interested, and Green Mantis because Jack wants a sparring partner/Punching Bag.

Asta refuses Golden Dawn because he wanna compete with Yuno.

Refuses Green Mantis because he fears Jack.

Now, between Crimson Lion and Black Bull, I wanna say asta would join Black Bull but that's unlikely due to Yami insulting him earlier because he's petty like that.

Asta Joins the Crimson Lion and the world is destroyed.

Because the biggest reason of Asta's growth is Black Bulls and vice versa.

With weak Asta; Elfs Succeed. Then Lucious plays uno reverse and turn them into paladins and finally the world is just like Lucious Wanted.