This is an old thread but I noticed something in Chapter 24 which gave me a double take;
This is from when Vin hears the bronze vibrations coming from the well of ascension the second time.
There are a few times I've seen facts change in the mistborn series but I mostly glossed over them thinking they might be Sandersons way of hinting at Ruins influence, but this is a clear conflict with Club's established ability to burn Copper.
ps - all of my Sanderson books are in Audiobook form so apologies if I mess up spelling of names or places.