So I think I'm done, at least for now. Things I did:
-Tweaked the location of the helmet and faded it a bit since it was attracting too much attention.
-Added some more foreground bushes to help the framing of the piece.
-Changed the position and posture of the farmost leg and foremost arm in the guy in the bottom. The way he was posed was dividing the composition a bit, so this created a bit more depth movement through the piece.
-Tightened up certain armor parts and added some highlights to both guys.
-Polished the moon's edge.
-Rendered the clouds some more.
-Added the feeling of marshes in the background - it was a bit too nondescript.
For now, I just have to wait and see what the Spectrum judges think in a couple of months. You never know if your artwork is what they are looking for or not. Here's hoping!