Yeah, I want to stick to a purple/blue color scheme like we see in a lot of the fluff art, but rust didn't seem a great color combo, thats why I decided to shift to more of a weathered bronze look . I found a neat example of this (the leftmost one is more what I'm going to try for I think), and I'm going to try to shift it to my color palette.
Wow... Found this neat tutorial while I was researching , may need to rethink my rune golems look now... Here is a nice rust tutorial on how to use chipping medium too .