I'm not sure cold blue is going to work well on an A-type semi-stainless blade. The fingernail polish may be your best bet, but you might want to look at this kit for blackening stainless steel:
Blueing is one way to go for sure. Didn't think of fingernail polish, but have used epoxy dyed black. Dab it in the grooves, let it sit and start to cure, then wipe off the excess with a lintfree rag and some acetone, or laquor thinner.
In regards to fingernail polish:
I use this in many of my hobbies and it is sort of a cure-all for things like Golf Club lettering, finishing fishing lures with either a topcoat, or a few coats on bare wood before sanding it for different paints on top (fishing lures mostly)
If applied properly it wont chip out, it is used in saltwater environments, dries completely and could sit submerged for hours with no ill effects. It soaks into the first level of most woods VERY well and hardens up to a rock hard epoxy feel. You can wipe away any standing on the surface of the wood with acetone and be left with a submerged sort of epoxy finish. Superglue (CA type) THIN such as ZapAgap will give an even better result on wood with lots of sanding and wiping involved, I wouldnt use it on the kanji though...
My ONLY suggestion is to use SALLY HANSEN HARD AS NAILS clearcoat as a topcoat or two or three (it is thin) over whatever other polish your using (I suggest sally hansen hard as nails for the undercoat). This is the one everyone on the popular leading message boards for golf/fishing like stripersonline.com or golfwrx.com I am speaking in this LAST paragraph about the kanji part...