An extra limb, if you will. That way the sword is the man and the man is the sword.
Only at such a level can true swordsmanship be displayed in all it's glory.
Once that stage of unity is reached between the sword and the man that wields it, then and only then can the true worth of the sword be revealed to the world and be of great use to the swordsman that wields it.
Thus, using this principle to explain the phenomenon that occurs during cultivation to the eight and final level, it would be right to say that this level was right to be called Union.
A situation that occurred after one had managed to cultivate their body to the highest degree and went ahead to do same for their bones whereby the Cultivator merges his body and bone after cultivating both sides individually to reach the highest point to become a single entity, a being that can command every part of his body to perform any task, as long as their mind is strong enough to handle the pressure that is.
