Putting rust pigment through an airbrush didn't get get the result I wanted. Just an even coat that only dulled the piece.
But I have another plan.
Anyway, I tested using graphite for metal effects. I picked up Graphite Powder at the hardware store, check the lubricant section:
I also picked up a really soft pencil:
I ordered up one of these as well:
And the results:
The pencil is really good for picking up a sharp edge, the powder is pretty good when rubbed on with a Q-Tip. I found that it can polished a bit after application. The sharpie is really bright, I used it like a highlight on the handle. Combined with washes and a bit of rust it doesn't look bad.
I think it would look best to show wear on handles and such.