I like it, no scratch that, LOVE it. Some comments:
+POSITIVE+ The metal of the knife looks real. The blood is spurting out from the wound the person madein his wrist. The eyeball is a strange color, which always adds abit of mystery. The shading looks great. The contrast between the skin and black background. The tattoo looks nice, good job on it.
-NEGATIVE- (stuff that I think looks a little strange) The knife is going into a bone Some of the blood on the hand doesn't look right.
Remember this is constructive criticism, meant to help not to offend.