Miyamoto Musashi is well known for “Nitoryu” (double-sword style) and the founder of his own school “Niten-ichi-ryu”. With Nitoryu, you attack with swords in your right and left hands. Generally, in you stronger hand you hold a tachiI (large sword) and in your weaker hand a dagger. Originally the Japanese sword is designed to hold the hilt with both hands. Holding it with only one hand or using two hands separately are very difficult techniques. Schools that majored on double-sword skills were rare, and that is one reason why MIyamoto Musashi became famous for his Nitoryu.
Musashi’s Niten-ichi-ryu is based on single sword techniques. The foundation of Niten-ichi-ryu is to be able to handle the sword comfortably whether it is in the right or left hand, and whether you have one or two swords. Its purpose is to adapt flexibly to situations where you have to fight in a narrow space inside or against many enemies at once. If you are fighting with a sword in your right hand and something happens that disables you from using your right hand, you need to be able to fight back using your left hand.
In this way, Musashi taught that one must be able to train hard to be able to use the sword equally well with your right and left hands. But training your weaker hand to perform at the same level as your right hand has positive effects neurologically too.
The right hand is connected to the left side of the brain, and the left hand to the right side. The development of the right and left sides of the brain are affected by the use of the left and right hands respectively. For those who are right-handed, the left side of the brain is more active, and for those who are left-handed the right side of the brain is more active. On the other hand, the side of the brain linked to your weaker hand is used less frequently than the side that is connected to your stronger hand.
Apparently when you use your weaker hand, it creates a certain discomfort, which in turn increases the oxygen in the brain. When the brain uses more oxygen it adds stimulation to the frontal lobe. The frontal lobe controls the ability to predict future results based on current active, making better choices, calming your emotions, and judging similarities and differences, It helps you keep your spirit stable and concentrate better.
Musashi might have trained in the double-sword technique as an effective tactic, but he may also have struck a method of using the brain more effectively. In his work Gorinsho, he writes instructions on keeping a calm spirit during battle and how to gain objective insight. He exhibited his talents not only with the sword but as an author and an artist. Perhaps his multi-talented work was based on his training with both hands.
For us, the only chance we really get to use our weaker hand is when cutting our own nails. Perhaps not many of us would use the sword with our weaker hands, but it may be interesting to try writing or using chopsticks more with our weaker hands.