When I was in high school and college, I practiced Bujinkan Taijitsu, a form of ninpo. My teacher always emphasized the fact that the weapon (katana, bo staff, or otherwise) is an extension of your own body. I think this is true. Part of the job of your brain is to create models of your sensorimotor system, this is called Proprioception. The holy grail of machine learning algorithms for robotics is an algorithm that can create an accurate internal representation of any arbitrary sensor set and understand how to use those sensors and actuators to act on the world.
In infants, this seems to be done by random experimentation and updating. Babies will twitch hundreds of thousands of times per day, exploring the reactions and most likely updating their internal proprioceptive representation; their internal model. In the same way that a martial artist learns to use a bo staff through practice, babies learn to use their central nervous system, retina, cochlea, and hands. Babies seem do it in an unsupervised, or at least self-supervised, manner.
Our body, sensorimotor system, and bo staff are just a small fraction of the technology that we have access to in the modern world. Bikes, cars, shoes, and clothing act as extensions of our body. Television and radio act as extensions to our sight and hearing. Language, writing, calculators, computers, and the internet act as extensions of our minds.
And, just like babies developing models for their legs which eventually become a natural extension of their proprioceptive experience, we develop models of our technology which become natural extensions of our biological hardware.