User blog comment:Tommy,Klaus&Kol2012+/why cant the soul be destroyed by fire?/@comment-34771833-20181224042848/@comment-3045936-20181226224205

Think of spiritual as thoughts or emotions. They aren’t physical themselves but they exist still. Spiritual is like on another wavelength or plane of existence. The physical realm can’t interact with it normally, as anything spiritual doesn’t take up space in the physical realm. This is until it temporarily comes into the physical world. Hence when ectoplasm is made when a ghost possesses someone or when Iron can harm it when they are more substantial.

A Revenant like the one in season 2, they are physical believed due to all of the spiritual energy surrounding them.