How do you get this weapon?
You get the Demon Layer from Lilian (need at least 1 sigil)
I will add this: do NOT use Holy Headpat on Sofia unless she is asleep (even then it does pitiful damage). I discovered the hard way that she thinks you are condescending to her and she will go full power and instantly knock you out. Have 8 spirit still? She won't care, she'll hit ya with something that will crush that in one move.