I gave Lydia several items to carry, including a simple mage robe that had zero armor rating. She carried it around for a long time in her inventory, and then suddenly out of the blue she was wearing it! And now she won't give it back. When I try to take the robe is says it was her original armor. Why did she equip a robe with no armor rating when she was wearing the heavy steel armor before that? Is there any way I can get her to let it go?