HI mate and welcome. I would do as Simon says. He is a wealth of knowledge. Also, I use a diluted stain to do my black first. It's easier to add black than to remove it and less sanding is usually required after the water/solvent has evaporated. If it's not dark enough for you, just do extra coats until you are happy with it. I've found two washes with diluted black is enough for me.

P.S. DO NOT use Tru-Oil over blue. It will yellow and turn your axe green eventually. A clear gloss finish is better.