We are cultivated, the futile ones are reaped, the beneficial ones are then reaped.
Sasatsuyu is the name of the cutting.
A cutting name is one of the names given to a Japanese sword when it is checked for quality.
For example, if a human body can be separated into two parts, it is called Futatsudo (two bodies).
It means that the blade is sharp enough to make your head fly off the moment you pay with an iaido sword, just like the water that splashes when you pay with a bamboo grass.