Not so long ago, in a park not so far away, the forces of light and dark gathered to … whack each other with expensive, glorified flashlights. In an all-day series of melees at Afton State Park, nearly 50 people — some from halfway across the country — went to war with glowing plastic tubes as their weapons and hockey, lacrosse and motocross gear as their armor. This is LED saber combat, a “nerd sport” in which Jedi knight wannabes duel with customized replicas of the fictional lightsabers made famous by the “Stars Wars” movie franchise.