Hi Adam that's looking very cool. With the marker pen I would test it on a small area and see if the blue darkens and it soaks in, or stain some scrap blue, let it cure and try it out.
Otherwise send DB an email or PM he may or may not recommend it.
Can you try another coat of blue stain ?
I'm confused with the kit model having an 'L' usually means left hand but this is a righty !