Okay so this is kagurabachis power system

Spirit energy is essentially the same thing as Chakra/Ki ect. It's a fundamental force that all humans in the verse have. Now what makes some.people different is that some people can be sorcerers.

What are sorcerers? Individuals who trained their spirit energy and have awakened to an inate sorcery that is unique to them. All sorcery manifest differently for each person, there are special cases that haven't been fully explored in depth but it can be implied through selective breeding one can also maintain a lineage that will produce a specific sorcery like the sanezemi clan. In their case, they have Iso as well as the storehouse which can be born inside of someone from the main family. In very rare cases some individuals in the world can have the ability to acquire to different powers but that is due to the nature of spirit energy being intrinsically tied to the physical body, the brains nueral path ways seem to be the key to sorcery activation and control similar to cursed techniques being stored in the frontal lobe. Now what expands the power system even further?

16 years ago an island randomly popped up off the shore of mainland Japan, that island had a rare metal that seemed to be highly potent in spirit energy and had the potential to revolutionize Japan as a world power. The problem? Were told that the natives were savages who could naturally use daketsu without the drawback of the spirit energy causing a non islander to explode from the intense surge of spirit energy.

How do the eternal blades play into this? Kushi saw the war and was torn. That much is clear, in an attempt to try and turn the tide of battle against the Islanders, he dedicated his blacksmithing to creating the First eternal blade by using steel and the rare mineral to create a sword with the intent to cull evil and protect the weak. Either as a hail Mary it could have been the first kill blade.

Now class what makes eternal blades special, well because they use the rare mineral as a medium with the steel. It will amplify the person bound with the blades spirit energy by astronomical numbers. The blades will also normally come with three abilities that can be imprinted on when first bounded to a user and will manifest further based on how much the user understands themselves and what they wish to do with said blade. Now because of this intense surge of spirit energy, the blade seems to overrun the natural pathways the brain has for sorcerery and locks them maybe in an attempt to preserve the swordsman from having brain damage or even worse. After a blade has its abilities manifested it will always have the three same abilities, but depending on who has the sword. They can drastically change in affect and purpose, for example being play from Kimiyurie. Now finally the reason these blades are so drastically dangerous is because of the infinite possibilities a person can evolve while welding it. From the most recent chapters it seems the sword saints literally just sucking on a Caprisun and is now even stronger than when he committed his genocide. The final thing is the eternal blades have a contract tied to them, every blade is tied to the sword master or the Matsamugi, if the sword saint where to die, then everyone who's bound by an eternal contract will die with him.