Hey Daya, that latest one has come on leaps and bounds from the first shots. Making the weathering rusty is a good move because it gives the metal a contrasting warmer colour to the blue body. It could probably stand to take a bit more noise on the flat portions, perhaps by adding a specular highlight on those portions (the directional illumination is already much better).
I think you could also get some more mileage out of that blue glowing bit at the back. If you can bake some fake blue reflected highlights into the surrounding portions it will stand out much more. You are working with the quake palette of course, but you might be able to switch palette rows to do it, using the lower bright blue row to find some more saturated highlight for the blue bodywork, and pale blue tones on the nearest metalwork highlights.
One final idea for the light itself, since the palette has very few fullbright blue tones it's hard to do anything other than make it totally flat. However, perhaps you could try a chequerboard pattern with the lighter shade. In software mode you might hope for an effect like:
http://i.ebayimg.com/00/s/NzU1WDE2MDA=/z/KpsAAOxyVLNS8SsT/$_35.JPG
In GLQuake the smoothing will at least create more texture and perhaps some kind of gradient effect.