User blog comment:Ornsteinthedarkhorse/Four Knights of Gwyn/@comment-16047389-20141124185056

I don't think the purpose of the four knights was exclusive to dragon slaying. Of all of them, I believe that only Gough was in charge of the Dragonslayers. Dragonslayer Ornstein may have only gotten the title for his efforts during the war against the Dragons. My theroy on it is that the purpose of the four knights was to act as the four "arms" of Gwyn (kind of how Velstadt and Raime were the left and right "arms" of King Vendrick), and would recieve their orders from him personally, and have all the authority needed in which to carry them out. Gough was in charge of the Dragonslayers (as can be seen in the item descriptions of the Dragonslayer Greatbow and Gough's Greatbow), while the other four knights served other purposes. I believe that Ornstein, while the leader of the four, was the protector of Gwyn himself, then later the defender of Gwynevere (then the illusion after she left), and possibly the leader of the Silver Knights. Ciaran was known as the Lord's Blade, though she was not the first (as the Lord's Blade Set implies that there were many before her), and through her dialouge and the descriptions on the items she uses, it can be implied that the "Lord's Blade" was a title bestowed to those that handled the elimination of enemies of Gwyn. Finally, Artorias was responsible for hunting down the servants of the Dark, which Gwyn feared more than anything else.