That could be. After all, he is a boss, and a former Cornerian knight. Perhaps they wanted you the player to have some idea of his fighting prowess. It's also a good reference for your abilities. He easily defeats a big dragon, so he's obviously powerful. That you can in turn easily defeat him gives credibility to your being capable of saving the world. If you can defeat Garland, it's believable that you're the real light warriors.