So did a few of the headshot one, let me know if I'm on the right track:
(I have a bias for this one )
I'm trying to find some of the Fatality ones and see if I can change the alpha layer, no luck so far. If I can't find anything I might just refine the one I made and add some blood streaks to it. At least that's something I guess :P As far as the achievements go, if there's some that are not part of an already existing chain (so, unique) I could probably throw in a few suggestions.