there are some threads here at pixelation that EVERYONE feels the need to make edits. This is one of them

To me though, I'd be much more interested in animating this bad boy at this stage. The version of the terminator you have now is really solid. I think you should listen closely to ndchristie's advise. Everything I'm about to say was already said be him, now that I look back over the comments...
I made an edit too


(animated, yours and mine)
and the palette: (yours on top, mine on bottom)

note: this isn't your full palette, just your main red ramp.
Like ndchristie was saying, Your ramp has some pretty ugly jumps right now. You have a red thats so near-black, that it may as well be black to the eye. I raised the value of that, and made other value changes in the palette to make a smoother, more evenly spaced, ramp. I also noticed that your second-lightest color, the gray one, was poking a hole in your ramp. This is because a gray (even though it technically is the right hue, just really desaturated) will tend to look cool in context of warm ones, and warm in teh context of cool ones. I raised the saturation towards a more yellow color. I also ramped the dark values towards purple, just for some extra interest. This alone, helped your sprite a bunch.
There were colors in your ramp that you didn't even use in areas of your sprite - making areas look more rough than they needed to be (such as the right, his left, shoulder pad). I added in those colors where needed - smoothing the sprite a bit. The last thing I think you should consider is lightening up the lit edges of a sprite. In the darker areas, it makes sense to have a dark outline, but in areas like the shoulder pads and back which are pretty bright, its quite a big jump to go straight to the darkest values for the outline. I tend to change the outline color dynamically with the color it surrounds - keeping it maybe 1 or 2 shades darker.
hope this helps. In all honesty, I'm much more interested in seeing this thing be animated than I am interesting in nit-picking it any further. You've made a wonderful progression this far.
-Dan