Just wonderinf if it is possible for your follower to have daedric armor equipped?

Not sure if all of them can. But I gave daedric armor and helmet to iona and she wore them both. Looked pretty bada** too!

Same as GreyNap, not sure if everyone can, but at least Farkas could. Equiped the full set too.

Jordis the Sword Maiden can not only wear Daedric Armor, she wears the heck out of it - looking about as good as anyone can look in anything.

I'm pretty sure all companions can wear what ever you give em, but there is a bug where they refuse to use the bow that you give em, they seem to like the default hunting bow even if the one you give em is far better.