Lookin good. Your costume is comming along at a nice pace. You go girl !!
Are you doing the silver scratches all topical ? or do you have a base silver layer underneith. Was gonna say I found that using multiple techniques for the silver weathering made the best results. If you have a silver base layer you can use an exacto and scratch away the blue layer (or whatever layer) and make nice fine scratches.(I used masking fluid, then went back and fine tuned and added smaller scratches with exacto). If I had to do it again i think I'd skip the masking fluid all together and just use the exacto to scratch/chip away to taste. This seemed to give me more control of the scratch patterns.
If your doing all topical use varied sized brushes to achieve this effect. I cannot stress enough how important it is to buy quality brushes of varied sizes. But I'm sure you already know this.
A quick work of advice if you are using mustard. Make sure its thick! I had quite a few areas that were thin. The mustard dired and I couldn't get it off. I had to sand the blue down and start again. I have seen others use mayo. I think this is a much better approach, as it really never seems to dry.