So i gave a full set of epic glass armour to my follower Lydia swo that she has better equipment than she already has but for some reason she refused to put on the boots or carry the shield. Instead she keeps using the old crappy iron ones. She happily wears everything else i give her and uses the better weapons i equiped on her. Anyone any idea why this is or is it just a glitch? Also i have noticed no matter how great a piece of armour i give her is she will not equip anything magical or anything i have had enchanted. Again-why?

lydia uses heavy armor. try giving her heavy and see if she wears all of it. if you want a follower that wears all glass talk to jenessa in whiterun (the taver just to the left when you come in the main gate.)

Thanks i will give it a go. I was just wondering if this was normal as she wears all the other glass armour i give her. The boots and the shield seem to be the only items she will not equip. She wears the glass cuirass, helm, gauntlets etc

This has to do with Lydia's defense values and skills.
If you check lydia she probably has very low light armor skill and its possible that the iron boots has higher defense than her glass ones which is why she is not wearing them :X

Edit: The only way you can check a companions skills is with console commands
Also if you are on pc I recommend keeping your companions leveled with you properly through the use of console commands.

Well i gave her heavy armour. I tried Steel, Orcish and Ebony. She wore the boots after all but nothing i gave her made her change from her lowly Iron Shield Maybe just a glitch of some sort.