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[spoiler]In .hack//INFECTION after you beat the gameyou can go to a bonus dungeon called Aerial Fleet, If you data drain the boss in this dungeon, Parasite Dragon, you'll get the strongest Blades in Vol. 1. Same goes for Vol. 2, After beating the game you unlock the bonus Floating Castle dungeon. DD the boss here and you'll get the strongest Blades in Vol. 2.[/spoiler]