I am in no way an expert on grammar, however, I will do my best. At best, I can tell you what is awkward..."He spoke not even a word as his feet landed heavily on the burnt ground, one after the other" - If others are there, it might be helpful to tell the scene from their POV. Plus, the last bit of the line was awkward, as if the "one after another" was modifying the ground, not the action of his feet.
"His bright blue hair did not shine tonight like it usually did as it flowed behind him in the wind, soaked with sweat and covered in so much mud it seemed almost brown." All of the pieces are there, but I would move it around a bit...maybe something like this "Soaked with sweat and covered in so much mud it seemed almost brown, his bright blue hair did not shine tonight like it usually did as it flowed behind him in the wind."
"His gleaming white robe was tattered and ripped from battle, his boots no longer shining brightly in the night, but glooming almost sadly in unison with the night" This sentence is just awkward. I would rework it. I can see that you are trying to set a mood with it, but it is just off.
"He paid no attention to the cheers of the soldiers around him even though they could have been heard by a deaf man with all their enthusiasm" I really like this sentence...it really "pops" and is a great contrast to the mood the MC is in. Which will set up this...
"Seracklen simply walked on with the stately manner of the king he was." We are establishing that he is a king or ruler of some sort, but the mood speaks of a "dead man walking"...someone walking to the gallows.
So, in the opening, we have an idea of the MC's physical attribute...though we will need to see a few more. He is regal...but dead inside (or that is the feeling I get). So, the transition from physical description to mental state can be flawless if you can link the outward results of whatever happened to his physical stature to his mental state.
All in all, good stuff. Keep writing.