Your opponent is Lars. Both of you have a shield and a sword. Lars is a little crazy and refuses to wear a helmet, but claims it won't be a problem for him. You graciously try to convince him to wear a spare helmet you have, but he refuses. He hits his head on a wall a few times to show you his head will be fine, so you finally accept his challenge.
You begin your duel out away from camp to make sure not to hit any passing folk. Lars' brother Bors is acting as the marshal to ensure your safety. At his call of "LAY ON!" you begin the duel itself.
You take one step forward and Lars immediately raises his sword behind his head. You think he may up to something. What do you do?