What Tx said.
Here is some real basics in finishes; Bluing is an oxidation process of the steel converting it into the black oxhide of iron, (red oxide of iron is called rust). This is why blued steel must be kept oiled. Ok unless salt from your nasty sweat is always going to be an issue.
Cold bluing is not the same process and offers little hope.
Parkerizing is the next best, an electrochemical phospate conversion coating.
Hard Chrome or sometimes called Industrial Chrome is not the same as the chrome plating on yur earring. Not only does it have the best corrosion resistance of the three, it has a very low coeffient of friction along with high wear resistance where the others do not.
The factory did not, or I din't know Hard Chrome was an option when I purchased my P3at years ago. I have some light rust on the side that faces my skin. This has occured from sweat through my Uncle Mike's & jeans pocket & my weekly choice of under britches. And ya, I keep it oiled.
When I bought my PF-9, I'll give ya one guess which of the 3 finishes I picked

Off subject, which of the Hogue Handall fits the PF-9?