Some Shield Ideas

So i had some ideas for the upcoming Arms and Armor book. Several of these ideas were floating around in my head but i had not addressed them as I am more working with weapons at the moment. Comments on facebook and twitter helped refine a few ideas. Now, as I am want to make a mountain out of a molehill and make the most complicated rules ever imagined, I am grateful for the grounding those comments offered. The shield's current AC bonus does not reflect its apparent real world utility. To wit, shields...

1. Shield absorbs one critical hit and is destroyed or rendered useless. 

2. Shield absorbs critical hits equivalent to its AC bonus and is then rendered useless.

3. Shield absorbs 1-x hit points of damage per attack. All shields are given hit points.

4. Shields are given AC bonus and hit points and then combine various rules from 1-3 above (I'm not going to do it now hahah)

5:  would minimally proffer a +2-6 AC. Hence, every attack roll against the character above their AC not adjusted by shield, removes one point from the shields defense until it is rendered useless. (See how i took something simple and made it complicated.)

6: Combine elements from 1-5 above making shields like adjunct characters with Hit Points, AC, damage reduction etc.... lol

7: Shield absorbs blow but has a chance of breaking

I am really trying hard to make this difficult. But, all things considered, the shield and armor need to be addressed differently - AS alternate rules. 

And, don't forget a shield can be used as a weapon. But there are a metric ton of shields types and differing materials used for construction. So... yeah, i will try to make some simple rules.