Depends on how "vintage" you want to go.

There are basically 5 different ways to etch.
1. Stamp. Use a die with the imprint you want to put on the blade. Put the die on the blade. Be the crap out of the die until the blade is deformed.
2. Manually engrave. Use hand gravers (little chisels) to shave away the metal. It's faster to do than you might think.
3. Chemical etch with ferric chloride (or nitric acid) by painting the blade with shellac except for the area to be etched.
4. Electrochemical using electricity and salt water with a disposable die.
5. Laser guided by computer (not exactly vintage).