i think this idea needs to be put in you can let people know not to need in it's not for them but that's not going to stop them from being a ninja. so i think grayed out and the companion option are good i also this if you hit companion then it should bind the gear to the companion so they can't just use it to sell!
on a 2nd note something to let you see if it's better then you companion's gear even when there not with you would make the game a lot better you have 5 companions am i supposed to know what there all wearing?