"Patina" is nothing more than an a variety of oxide that either forms or is induced (via chemical reaction) to form on the surface of steel. The "base" material remains the same, along with any issues inherent to the material, and while some surface oxides can enhance certain characteristics, nothing is gong to be what I would call "durable" when it comes to carbon steels. The best candidate I have found is a baked on finish such as Gun Kote..... but even that will scratch, etc with time and use.