This isn't quite magical on contrary it is history however within history we learn about social roots. Social roots tell us more about
It was a long standing belief within the Samurai that weaponry was very much alive and if used in combat it desired more. Once it tasted blood it demanded more.
Now this simplistically is just superstition but rather if you think about it then you begin to understand a rationalization of their own lives. They theoretically give their lives in service to their weaponry's desires rather than murder of others.
Just a rambling of mine. Take it how you will