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.
