This is just the basic designs. I currently wondering what I should add to Mari's design, such as replacing her human form's ribbon headband with something else such as a head ribbon similar to Cirno or Mokou, or ribbons similar to this art of the fanmade character Michel Sant'Angelo:

Despite her Wiki description is describing her wearing two ribbons, actually it looks like she is wearing a single ribbon, so maybe I should draw a single head ribbon instead. But which style? Cirno, Mokou, Utsuho, or Sekibanki? or a single ribbon on a headband?

For the cape's inner design, actually I want it to be something impressive but of a simple motif, such as the sky design in Utsuho and Chimata's capes. I don't want to add pentagrams into her cape's inner side anymore, since that might be too "occult". Overusing crosses in the design of characters that are related to Christian themes probably is a bad idea. But since in Christian symbolism there is mention of the elements of fire and water, so I think I should make the inner side of the cape to look like either stylized flames or streams of water.

For the shoes, I have the tendency to draw flats and Mary Janes. And to me, drawing each character wearing the same flats and Mary Janes make them look like they are created from cookie cutters of anime characters with the same shoes, which to me, is quite boring. But I haven't drawn any characters in boots (like Michel above), so maybe I will give it a try by drawing Mari's angel form with boots.

If you ask me about the left hand looks like as if she is holding sometihing levitating, then I would say that I initally want her to hold a red heart-shaped Pneuma Core (a concept in my fangame series that is derived from Undertale's SOUL concept) to symbolize her soul when she was still a human, but since that might be a too obvious reference to Undertale and might struck with copyright issues, then I need to replace the appearance of the Pneuma Core with something such as a "spirit butterfly", like those on the current cover of the game (but I'm going to replace it soon, but still retaining the "spirit butterfly" motif)

That's just my intentions for now. If you have any ideas for this character design that you want to share to me, just shout to me or leave a comment below. I will appreciate all of your ideas.