Thank you all for your replies!
@Renamon: Modeling is the easy part, making it look good is the hard part… Yes the writings on the armor were made using text controlled by curves and the chains too.
@abalaich: I used an HDRI light for the reflections on the metal and a 3 point light setup to light the Grey Knight and make him stand out from the background. I tried using a stronger rim light but it lights up the fog too much and makes the background disappear. I could though enclose the whole scene in the corridor to make the armor reflect it, since now I used the corridor only where the camera can see it to save up on pc resources and render time.
The lightning actually casts a reflection but it is so faint its hardly visible, that’s mainly due to the fact that all the lights have an emission value in the scale hundreds due to the volumetrics and the lightning has a value of just 5. I didn’t make it brighter in fear that it will become too bright and the detail of the lightning and the halberd will get lost in the glare. But you are right on that, I could play a bit with the value and see what happens.
@PawelBrzu: I was thinking about adding DOF but I actually got lazy but you are right, I should add it. I’m already using glare to blur the lights and the lightning but I haven’t tried out the Fog Glow so I’ll give it a go and see how it looks.
The model is intentionally brighter than the corridor since the main purpose of the scene from the start was to showcase the model. I don’t know if it looks weird this way but I could try to make a test render with only the corridor lights on.
As for the brightness of the shoes in contrast to the floor, the way I perceive it, it’s natural since the armor is much more reflective than the floor. If you put a tin can on a rusty plate and light it up with a flashlight, I feel you’d get the same result more or less.
Thank you all again for your input. I’ll make some changes based on your suggestions and i’ll post some new renders soon. (It takes ages on my pc to even preview the scene let alone actually render it :P)