You will want a much cleaner base mesh if you are going into Zbrush to do some sculpting. For example on your edges if you try to add any wear or detail you are going to get some horrible deformation because of the polygon distribution (I assume) and the extreme sharp edges. You should take a look at some of the tutorials…
I think you could tighten up your material definition in the sculpt. Texture work can help a lot here but I feel your cloth bands are looking a bit "blobby" probably because of the method you used to sculpt them. Similarly the bottom section of the weapon, which read as a small sharp blade on your concept art is looking…