He was the first one to be called a Beater, a combination of beta testing and cheater, as he had great knowledge of the game through the beta test period and showing great skills in floor clearing but chose not to help other players.
He had it imposed on himself so as to differentiate the beta testers who were just picked in the testing and the serious gamers who uses the knowledge efficiently like a cheat.
Kirito tends to use a single handed straight sword. The blade that he uses most often is the Elucidator. Later on he acquires a second blade called Dark Repulser that was made by his blacksmith friend, Lisbeth.
Read more at http://myanimelist.net/character/36765/Kazuto_Kirigaya#LMAe4oJXGmD5l7mC.99
Kirito wanders in an unfamiliar world in order to gain any clues about the "Death Gun." Then, a female sniper named Sinon who owns a gigantic "Hecate II" rifle extends Kirito a helping hand. With Sinon's help, Kirito decides to enter the "Bullet of Bullets," a large tournament to choose the most powerful gunner within the realm of GGO, in hopes to become the target of the "Death Gun" and make direct contact with the mysterious avatar.