This would be better described as a ray of light than a blade, seven inches of time, in the blink of an eye; clearly present one moment, and gone the next, hard to grasp.
"For there is time in heaven and earth, capable of slashing ghosts and gods..."
Zhou Dao gazed at the blade before him, his eyes misty and dreamlike.
The greatest power in the world is the passage of time; under its influence, even heaven and earth will age, and ghosts and gods will decay.
The appearance of the Heaven-severing Blade was like a segment of time, severing the fetters of heaven and earth, the constraints of the void; with that one slash, came great liberation, great freedom.
"The Seven Kills Sect... This is the Seven Kills Sect..." Zhou Dao murmured, as if he had gained a new understanding of this enigmatic sect.
He stepped forward, reaching out with his right hand towards the Heaven-severing Blade within reach.