There are two categories of all things in the world: living things and dead things. Living things have spirits. Spirits give things the thought of living, while dead things have no thoughts.
It's like a weapon controlled by someone.
They cannot become alive.
Except for one thing.
A cruel forbidden technique passed down from the world a long time ago.
Sacrifice the blood of thousands of people, bury swords into mountains, until they tower into the clouds to become spirits.