It's an allegorical intepretation of the scene, focusing on symbology rather than a literal depiction of the moment.
I looked for inspiration in Renaissance painters like Caravaggio or Bernini's sculptures. I think I've been exposed to those artists more than I ever realized (growing up in Italy) and I like those poses and expressions. I tried to do something along those lines and use very strong darkness and accentuated light sources on the points of interest.
It was really challenging. I changed the Nazgul once, the mace three times and the sky at least twice through the process, not to mention how much I worked on the female figure. I had no straight reference for that, so I had to look at several things, none of which with the correct light source, so I had to make that up. A lot of trial and error.
On the other hand, the sliced volatile was fairly easy.
Final size: about 3100x3600, Photoshop.