As to PoR and it makes sense to me. It's both. Metal when it's unleashed and powerful. Leather when it isn't. Of course, LoI had it unleashed, I'm sure, and it wasn't metal. So it can't be "conclusive."
But that makes sense to me, it also works with the older games on how you upgrade it.
I know people hate PoR. And I do too, for the most part anyway. But what it uses, seems to make a good deal of sense in it's appearance.