In my opinion, all of powers that use such creatures as demons, angels, spirits, souls and so on assume that author will determine what they are. Have you noticed this wiki never states what is dome creations? Leviathan Physiology is the ability to posses traits and properties of a leviathan but this wiki never says what that damn leviathan is. As the fictional author, it's you the one who needs to determine this. Let me show two examples.
In Black Butler there are such creatures known as demons. They are completely evil and make contracts with humans taking their soul. Demons are evil and there's no good in them. All of their kindness or politeness is fake, they just pretend.
In Highschool DxD there are demons too but they aren't so evil at all. They are immortal peaceful and carefree creatures who just have fun and enjoy life. If there was a character in Black Butler who possessed abilities and traits of demons, this power would be Demon Physiology. Yet if there was a character in Highschool DxD who possessed abilities and properties of demons, it would be Demon Physiology as well despite those characters posses different abilities and traits. You see, there's no list of specific "abilities and traits" neither there's no definition what that creature is. It's up for us to define. So, spiritual existence may both be energetic or etheral depending what you will choose.
I believe that Aether is the creative metaphysical energy of reality, i’m pretty sure that Spiritual metaphysical energy comes from aether. I believe that the Consciousness or psyche is produced by both the physical and metaphysical energies of our reality, The biological physical energy is channeled through the nervous system and brain, While the spiritual metaphysical energies of the astral plane (Metaphysical Reality/Great Spiritual Reality) Record, Preserve and Augment both The psyche and Uses The biological data collected from the material body to create a sort of spiritual body (The Astral form) for the consciousness to exist in after death.
To recharge one’s spiritual energy requires prayer, meditation, Love, hope, faith and belief....
also the ability to channel cosmic energy And convert it into life force.
What do you think?