Okay, so first post ever, probably filled with holes but here it is.
I have a theory that lightweavers could actually shapeshift, especially Shallan.
Why? Well, Stormlight healing works on their spiritual identity, and how they see themselves. So, what if a lightweaver such as Shallan could make a new persona, always wear the illusion until they “are” them, and then would that cause them to heal looking like said person?