A massive undertaking, to say the least.  Postwork is going to be extraordinary. 
Suggestion: Throw your background out of focus in post-production.  It is too sharp and detracts from the action going on in the foreground.  You don't want the eye to wander to unimportant areas.

The image is too sterile; it is too clean.  It is a battle scene, there should be debris everywhere.  That includes body parts.  The armor should have gritty dirt and stains as well as plenty of dings and dents. 

Smoke.  Lots of smoke.  A haze of smoke over the scene. 

Spend some time recreating more realistic poses.  The figures look too stiff, not much action.

Tip: watch the first twenty minutes of "Saving Private Ryan", that should give you some ideas.