What does the Dual Cast Alteration perk do?

[DiagorasRadix]

I can't check at the moment. Does it double the duration of something like a Flesh spell, or double its added armor value? On a related note, is there a way to hit the armor cap without wearing armor (with the exception, perhaps, of using a shield)?

 

[Onyx]

I believe duel casting in this case increases the duration.

There is a Mage Armor perk that increases the armor bonus (up to x 3 I believe) as long as you are not wearing any gear that provides an armor bonus.