What are the 2 cursed katanas?

I'm curious, could you please elaborate on the concept of the '2 cursed katanas'? Are they fictional weapons from a story or folklore, or are they perhaps a metaphor for something more abstract? Are they known for their mystical properties or for the ill-fated fate of those who wield them? I'm intrigued to learn more about their origins, legends, and potential significance in the world of folklore, literature, or even modern culture.