[@An Outsider] Sure! Although, I'd like all of you to participate in creating this story, too. Feel free to add in any blancs or details you think I've missed.

The knights are strong, muscular fighters with heavy melee weapons and horned helmets. They wear heavy-ish armor and ride on big destriers. Think Tulsa Dooms riders in Conan the Barbarian. 

The wyvern is a giant two-legged winged reptile with a long neck and a barbed tail. The tail drips with a deadly venom. The rider is a fierce warrior, armed with a great haleberd.