I have never read, never been taught, and never have experienced bluing as a good corrosion inhibiter. If something has changed in the past hundred years please educate me but even professional hot bluing does not offer much in the way of corrosion protection.
I've done a lot of hunting on the Alaska Peninsula and the islands where liveing in a tent with days of rain and wind will rust a gun quite fast! I had one of my guns "rust blued" the old way, and it's amazeing! Everyone would be working on there guns daily, but i never had to do a thing to mine. It's done rusting, and to this day it does NOT get rust on it. I rarely wipe it off with anything but my hand and i've yet to ever see any rust on it.
It wasn't cheap, but for me it was $$ well spent, not to mention i really like the way it looks.
DM