To me, it almost looks like the finish/stain hasn't bonded particularly well to the quartersawn grain and has worn off or flaked off. I'd probably go over it with a 50/50 mix of meths and turpentine with some 00 wire wool or fine scotchbrite and see what happens, if you can remove the finish in that area completely it will be easier to re-do or alternatively go over the whole piece and re-finish the lot which would be quite time-consuming.
That brass pendant might be the most awkward thing to replace on the whole thing, If you wanted to get a replacement I think you'd need to have one made.
I did Furniture Making and Restoration for a year when I left school, it's not often I use what I learned there in my every day but once in a while a little gem of knowledge in the back of my head comes up trumps and saves the day.
If you haven't already got a copy it's worth picking up "How to Restore and Repair Practically Everything" by Lorraine Johnson, a good book packed full of info and it's literally what it says on the tin, plus its peanuts to pick up secondhand.