Mineral oil is preferred because it won't go rancid, such as around the joint of the handle and the blade where it is hard to get all oil out during cleaning. Also won't go sticky on the wood and is a food safe oil.
Patina is a form of controlled rust that mostly neutralizes the reactivity of the blade surface. One will form slowly anyway unless you actively remove it. Forcing the patina means to use a method to accelerate the patina formation intentionally. Off the top of my head we've talked about using things like potato, banana, vinegar, mustard and so on.
Using produce, you just stick the blade inside of a potato or two for a time.
With the texture on your blade a potato may not give you an even enough patina, so a vinegar bath would probably be better.
A green scotch brite and some scouring powder will remove a patina.
