Hot bluing is definitely the way to go.
Of course, it’s a dirty, corrosive business. I’d send it out to a shop that specializes in it.
Hot bluing by a pro is the way to go. How many of us could successfully spray paint a car after spending hour sanding it down in preparation?
I do lots of things so I am not afraid of doing things myself, but this is for pros if you want a pro finish.