From the little I can see of the scales, they appear to be ivory. If they are then there is no way you have cell rot. To have cell rot the scales need to be made of cellulose material, which many were. Better photo of the scales might help determine better what they are made of.
Bob
Τhanks Bob and Mike for your answers. As for the scales with my little experience I think it is ivory. If so I can not explain the yellowing on the blade. I also send photos from the scales.