yeah it needs more contrast, saturating it more will bring it out more, but this guy looks pretty creepy as it is, which is probably what you were tryin to achieve..
If you simply brightened up each colour atm it would look friendlier on the eye but certainly not as effective as you first atended it to be.. I tried to work on the character you made but I just found the dithering too unecissery.. and it's just too complicated to tweak the colours to what you maybe would of wanted.. Anyway im just making a mess of it..
I decided that your original linework maybe looked too stiff, everything looks a bit robotic, and square.. this executioner is definately a fatty, so I don't see the need for pex.. maybe a hairy chest?
Plus I go for a good old butcher knife
.. Should be bloody but im not too bothered, as its only a quick example.. Just make sure you're character looks natural.. And with the colours, I think it helps to have a few of the same characters next to each other so you can try out colours and experiment, theres no harm in it..
oh and aliasing can really help smoothen your work out, usually inside your lines, not to the backdrop but what the hey..
oh and don't judge my example people, I used the same structure as araknidkid's character.. The colours may not be perfect but I triedAA'ing if your confused is explained well ere..
http://en.wikipedia.org/wiki/Anti-aliasingHope I helped..