It would look mostly like play. Have you ever seen two young kids spontaneously wrestle? Spontaneously use wrapping paper tubes or sticks as swords? Imagine if that kind of playfulness was funneled through a culture that saw athletic play as an important part of skill development and knightly training. Play also developed into elaborate ritual games like tourneys, jousting, shooting festivals, and hunting.
I've written quite a lot about this topic, if you'd like to read more.
How would I go about hiring someone like Fiore to teach me fencing??