The blade is clay quenched with a hamon. I polished it to bring out the hamon then put then handle on.
I wasn't very happy with how light the maple was so I experimented darkening it with muratic acid, which was a flop. (I now have the magical stuff sold by R.W. Wilson). In the process I got some of the acid on the blade and ruined my mirror polish with a black spot. So I decided to turn it into limonade
I put several small drops of mustard on the blade and let it sit overnight, then wash and repolish. This was done every night for about a week. The circles are from the outline of the mustard drops.
Hope you like.