I think the first thing you should do is take the valkyrie apart. You don't want to try and remedy the problem with the valkyrie fully intact.
From the looks of it, it seems as if what you used had a bad chemical reaction that actually melted the parts in question.
You might want to consider wet sanding the part with 1200 grit. Then, once the part seems somewhat smooth, polish it with a dremel tool and polishing attachment.
Other than that, you either find replacement parts or paint it.
Just remember when restoring a toy, it really is about patience. You must not rush the process of wanding as it will damage the parts further (loosing details and such).
If you are coming to the Con, bring it with you and I'm more than sure I can help.
Remember, patience is the key.
NB4M