Thanks for the feedback, everyone. It was very helpful. I widened the handle wraps, made the horns more knuckley, elongated the nasal cavity and added some more dings and scratches.
@BluPanda - I considered 3 options for the skull:
1) Skull face on the front and back of the skull on the other side.
2) A squashed skull on each side.
3) One skull with a face on both the back and front.
I decided on method #1. It seems to add some depth and realism, as well as having the other side look different, but I'll have to sacrifice some texture res. We'll see how it turns out. I may regret it. #2 would have given me problems with the horns and spike.
@hannes d - The blade spikes were probably the part that gave me the most trouble. I'm past the point where I can majorly change them now. I'm not super pleased with them, but it's time to move on.
I guess it's time to do the low poly and bake, unless anyone can see anything else I could improve with the sculpt.