I see now..

Thinking back and now, Yuno is always gonna be one step stronger and more gifted than asta and has the potential to be a king but the difference with him to asta is that Asta HAS the makings of a king, he has the power to influence people, he made people respect him though hardships of his own, he wasn't gifted like Yuno but he somehow made the people see he has the qualities of a king and I think that's how Yuno we'll be second to asta in terms of being the future king