Sorry if this is old news, but I can't find a good answer on the various wikis.

I tried smithing a set of light chitin armor to Legendary in order to give Sero an upgrade, but he won't equip it- he just stays in his default set.

Is this a bug or is there something I can do?

I am on Xbox 360.

Thanks!

I can't get him to switch armor either. Shame too, he's a badass looking Dunmer.

He equips stuff that I give him. I even remove his helmet.
Xbox.

You can get him to switch armor but apparently it has to be light armor but the helm can be anything with higher armor rating. I got him to wear legendary light stalhrim armor and a daedric helmet before he disappeared