"Rotting scales". Now that's an interesting concept. The Special does have fancy celluloid scales.

Celloloid is made from nitrocellusose, and decomposition would result in nitric acid formation, which certainly would be corrosive. I will look into seeing if any acid gas formation occurs and report back.

On the other hand, the corrosion is only where the prior rust spots are. So it would seem something catalytic is happening where the pitting is. I have sanded these spots smooth with fine emery cloth, but slight discoloration remains. Perhaps I need to go deeper, and waste the etched pattern on the blade to do it.