I'm all for the blocky retro style, like ptoing's chunk-funk for instance, but here it's too subtle. It feels more like a mistake, like stiff lineart. Though I do enjoy the mountains.
Lovin' nd's shadows/highlights and color edit -minus- the darker bg. A lighter bg may result in the foreground popping a bit mo'. Right now with the mountains having such a large luminosity range their drawing my eye too much. Lessen that contrast?
A cute girl character holding an ugly severed barbarian head. It don't jive for me. Is the unlikely contrast intended for shock, comedy, etc? Her clothing - she'd freeze in 3 seconds. Though, I suppose you're applying the less-armor-is-more-armor in the case of fantasy women characters. And I do like that cartoonish concept, even yet it's still a little "funny" to me. Her arms appear to be differing thicknesses.
At first I thought the barbarian head was receiving warm and cold light on either side of it's face, but it's not is it? It's the typical celtic facepaint right? I can't help but think there's a large fire burning just outside the pic, to the left.
The blood-trail implies a path, but there's no footsteps to go with it. Adding them would be logical but, also yes, add more "noise" you may not want since this style is so minimal. I'd probably ditch the blood drops falling from the blade.
Some falling snow perhaps?
Compositionally thinking, it seems your negative space should be flipped - give it less hill and more sky (pan the camera up, keep the dimensions).
Got an unused green there? Is this a pre-made palette?
