I had originally planned for the scales to be just part of the puzzles, and for what Diane was after to be something else. I'll elaborate on what it was going to be later, though fair warning, it's not particularly exciting.
What I realized, however, was that a lot more of this nonsense adds up with this dungeon and fairy Ashley if it's the scales, including why the last part was the way it was. I also like the reason I've come up with for Diane wanting the scales.
It would also be a bit weird for there to be two artifacts with the one at the end was just some other thing Diane wanted. I like it simply being the scales better.