My suggestion: Paint over them in a coat of black (enough to remove the legends) and then finish with some kinda varnish.
I build a lot of Gundams so I'd use this stuff:
Show Image
(http://gwing-online.com/images/categories/Gloss.jpg)
I've had cans of black paint that were very shiny, so you might not even need to top it off, but it'd be good to protect the paint.
But its probably not wise to make "shiny" keys, since your fingers would wear out the finish/paint on it anyway.
What was wrong with your WASD keycaps?
Seems legit!