when i finished azuras deadric quest the black star i took areana lenith as my follower. Being the arch mage of the college if winter hold i gave her the arch mage robes, morokei, steel plate gauntlets and boots. But occaisianly she decides to take the arch mage robes off and follow me around wearing morokei, gauntlets and boots but not any cuirass is this a glitch or what!

Her default clothes are "hooded" and have no armour rating if you give her head gear with an armour rating she'll drop the hood and therefore the robes. She is probably treating the Archmage's robes the same way and the patch that fixed Morokei doesn't work for her.

Aranea is skilled in Light Armour, so you will get the best out of her if you use that anyway. I gave her all Elven gear with different schools of magic enchants - she's a good all rounder. I also gave he all the staves I could find and took her weapons off her.

Here's a video of her in action with my Dunmer Spellsword

http://www.youtube.com/watch?v=J3mwrQrBl7g

I dont have online so i wouldnt have gotten the patch but sometimes she does wear the robes she just decides to take her clothes off its really weird but i will be sure to give her eleven arour when my enchantment is higher