It looks to be in very good original condition and great care needs to be taken when trying to do any preservation/restoration work on an item such as this. As I have already stated I wouldn't recommend using any strong chemicals such as Naval Jelly on this bayonet. You could soak the metal part (not the wood grips) in diesel or oil and then try rubbing lightly with medium to fine wire wool on the non blued parts where required. Looking at the pictures it doesn't appear to need much doing to it and I don't believe that you will find it possible to remove all the staining.