Drexel Biscayne Dining Set  

If you
were planning to sell the piece(s), I would consider giving the purchaser the option of receiving (them) cleaned or "patinated" -- putting off the decision to the next owner.
A gentle but thorough cleaning with a little liquid detergent on a clean sponge (followed immediately by cautious rinsing, and drying with clean cloths) wouldn't remove any of the actual aged finish, would it ? Anyone ?

my two pence on patina
though i've never been accused of being a patina expert, it would seem that anything that would wash off with water, a mild detergent and a little gentle rubbing wouldn't really be a fair candidate for the patina badge.
it seems a patina on wood is typically a darkening effect as a result of exposure to air. [the same process to metal is oxidization.] am i correct in stating that wood exposed to light creates the opposite effect, a lightening or "bleaching" of the wood? yet in both cases, the visual surface of the material itself [as opposed to what is "on" its surface] is altered.
it doesn't seem consistent that simply an accumulation of matter could be rightly labeled patina. before i moved into my current residence [built in 1927], the elderly woman who had lived there smoked like a freight train. not once did i consider all of the tar i washed off of the painted woodwork to be the coveted sign of aged beauty.
maybe we apply the term "patina" only to a desirable change in the appearance of an object, contributing to its charm and value. and to take it further, any undesirable change we usually classify as "dirty" or "damaged".
hmmm... perhaps more questions than answers.