The skull and predator's hand lacks texture and looks cartoony. Predator's wrist looks swollen. That being said as a fellow artist, hands are by far one of the hardest body parts to draw. The skull and hand portion just doesn't match the detail in the rest of the artwork, which is very good. Sorry if I come off super critical, I just feel looking at the rest of the artwork I know you have the skills to give it the same detail.
P.S I will be making my payment in full next week.