Yes, you can enchant robes. But they aren't armor.
They are wonderous items. And if you want to make a Shirt with +5 ac...go for it. It would cost exactly the same to make a bracers of +5 ac.
You can't make +2 mithril ROBE of frost resistance by conventional methods...unless of course, you calculate it out as properties for your unnecessarily expensive new wonderous item (and spend a bunch of money getting mithril thread made even though it's heavier than cloth...hehe).
They are wonderous items. And if you want to make a Shirt with +5 ac...go for it. It would cost exactly the same to make a bracers of +5 ac.
You can't make +2 mithril ROBE of frost resistance by conventional methods...unless of course, you calculate it out as properties for your unnecessarily expensive new wonderous item (and spend a bunch of money getting mithril thread made even though it's heavier than cloth...hehe).