I think it could do with a very watered down black and brown ink wash over it (separately black then brown, not the two mixed together!). The ink washes would add that real world look to the weathering. Aside from that I like it.
thanks guys, yeah.. these pics don't do the weathering justice unfortunately. it is really washed out in the light. In person it is pretty dark. I will work on the weathering a bit more though. thanks for the input!