It's actually more complex than it looks, and difficult to describe... Basically the Armor itself loses 2 AC. You get 1 back from the Enchantment... but also an AC bonus equal to your Charisma modifier or +2 (whichever's lower)
In 3.5, this would be much more useful since it could stack with other bonuses. However, in 4e I've decided to make that AC bonus transferrable to Reflex, Fortitude, or Will as a minor action.
Heh, sorry, I'm afraid I still don't get it. Let me talk through how I see it, and let me know if I'm right.
With Glamorous Chain +1, the chain AC goes from 6 to 4. However, the armor check penalty goes down by 1, and the speed check penalty goes down by 1, to 0 each. The +1 improves the AC back to 5. Then, as long as you have 2 or more charisma, you get an extra +2 to your AC, making it 7 ac, no armor check or speed penalty, half weight, and with a power. As you say, that's pretty darn good!
With Glamorous Chain +2, the chain AC goes from 6 to 2 (For every step in enchantment, this item reduces the armor bonus of the item by 2). The armor check penalty and speed check penalty still go down to 0, no change. You still get 2 from your charisma, and an extra+1 from enhancement, giving a final of 6 AC, no armor check or speed penalty, 1/4 weight, and the same power. By my reading, you pay more money, lose 1 AC, and get 1/4 off the weight.
Or... do you add 2 to the potential charisma bonus each time, so at the +2 enchantment level you can add up to +4 for charisma? That IS good.
Anyway, that's how I'm getting confused. I did go ahead and get the armor anyway, because I want to be sexy, but I figure I must be doing something wrong with either the +1 or the +2 version. Really, though, it's no big deal since I went ahead and bought the stuff anyway; just let me know if I need to make any change! And thanks for spending time reading all my questions; hope it's not too much of a bother!