Dear All I have recently acquired from a fellow member this yamagane/copper tsuba:     There is some spots of verdigris here and there. If it was rust on iron I would soak it with choji oil and then scrape it gently with ivory, bone and antlers splinters. With copper alloys I am not sure of the best way to proceed.  There is some simple procedure that I can follow to improve the appearance without damaging the underlying patina while removing the verdigris or it is