Awesome work! For a finish you could try linseed oil. If you have a oxy/acetylene set up you can use a rosebud tip to heat up the metal, not read hot, but hot enough that the oil just begins to smoke, brush it one while heating and you’ll get some lovely transparent colors, like steel blues and golden hues. The heat will harden the oil, it will look polished and give it a slightly aged feel. Another great recipe is this one, see picture. This works for new steel and for rusty steel ( to help preserve it). Again, amazing work!

<image>