DIY reblueing effect on value

[Atom]

I have a Walther PPK/s bought new in the mid 80s. It has been stored but not sealed and has developed some spots of cosmetic rust on the frame and slide. Otherwise in perfect condition. I bought a blueing kit but have been told by two different old hands at the range that it is a collector’s item and the reblueing would decrease its value. Opinion? 

[KahrMan]

It would lose most of its value for collecting if you reblue the spots. The rust spots will decrease the value some but the reblue will drop it even more.