It definitely needs a background. Maybe something with dark greens or blues in it.
Don't shy away so much from light colors! it needs more light especially in the figure!
I love the way you rendered the laser arm thing, the swirls and color change are well done. I think your character needs some lighting on them from that light source though. I also think some variation in background would really give this more depth.
I like the laser and the yellow garment part that glows. Maybe you could add the same design onto the other side of the yellow garment. I would also add more to the background so your piece has more depth and you can make your glow stronger.
the sword is very glowy, but still very graphic and vector
I like the way that you have him coming out of the darkness - but I think you could push it even more! Since you have such an awesome light source in here, I'd love to see you use that nice green glow from his sword to highlight the side of his helmet and armor! LIke - it could cast a green light on just some of hte edges! I like how youre introducing some really nice gradients into the ways that his arms turn in space - keep going! It would be cool to see you use that in his lower half a little more! I also think you might be able to use a couple different outter glows on the sword so that the light eminates even further and really seems organic!