dragon slayers were created to battle against dragons in the dragons civil war
normal humans are useless against dragons, in order to kill a dragon you need a wizard that uses the dragon slayers magic with the ability to go into dragon force.
note Rogue and Sting's DF was incomplete and lacked power. you will find about those two in the later chapters
Sorry to bring in the news, but this one just got updated again not too long ago. I'm not terribly interested in the game, so feel free to take your time to update it. 敗戦隷姫エルネア to v25.04.23