Xu Fan, of course, knew that the so-called strength, regardless of age, means if someone is stronger than you, they can stand above you, even strike you down!
However, Xu Fan inferred Arthur's temperament from his previous behavior: a gentleman!
That's why Xu Fan said those words to provoke Arthur into accepting his wager.
To put it bluntly, those words were just a little trick by Xu Fan, effective against gentlemen but not against villains.
At this moment, Arthur's knuckles cracked as he clenched his fists, "What's the stake? Can I set it myself?"
Arthur didn't ask what the bet was about but directly questioned what the stake was, showing how much he wanted a legitimate reason to punch Xu Fan.
"It must, of course, be agreed upon by the other party. If I win, I want your understanding of the Domain."