Although Shangguan did die, he would have won easily if he hadn't given in to his overconfidence and challenged Li Xunhuan to throw. I don't recall the exact words, but I believe that Li Xunhuan actually conceded the fight once he realised he would never be able to throw the dagger, meaning that Shangguan Jinhong technically already won the duel. What happened next, whether Shangguan Jinhong kills Li Xunhuan or vice versa, would just be an afternote.