Everything inside the ethereal blackness was part of Noah's power. He could draw the abilities of all his companions and use them in one attack, but that wasn't the end to it.
Night, Snore, and the other assets inside the ethereal blackness could also benefit from that ability. They were part of Noah's world in the end, so they could use certain aspects of their companions' power.
Philto was a troublesome opponent that raw power couldn't overcome. His mark on the universe stood deeper than what Noah had to face against Cursed Realty and Caesar, and Divine Demon had shown how an all-out attack wouldn't work.
Noah's offensive had to be more specific to reach the depths needed to affect Philto, and Night was the perfect companion for the job. Its ability to seep into worlds and sever unique targets was unparalleled, and Noah had every intention to empower it with the entirety of his destructiveness.