Do not be afraid, it's a pure metal, there are NO plating. 

Walking stick held at atomospheric agents for 2 years without maintenance.
In a few seconds it returns bright shiny as originally.

First pass with a 0000 grit iron wool. With a few steps you will have removed the superficial patina, and you will see the shiny metal

With a cloth and normal body abrasive paste (the one used to remove scratches from the car body), after a few steps you will see the shiny metal.

Afterwards for a good maintenance, wash with normal neutral soap and tare. It will be enough to maintain the original brilliance.