"My only love in my life is the seven-foot sword, which kills me when I see that I am not myself." What does this mean?

The only thing I love in my life is the seven-foot sword, which cuts me to see what I am and what I am not. This sentence comes from the fantasy novel "The Honor of the World" written by the diving squid. The heroine Jiang Zhiwei said goodbye to the hero Meng Qi before she died. The meaning of the poem is that what I love most in my life is kendo. After entering the death barrier, I will fight with myself and cut off my past self. I will not be the original me.