1. When you play armor, can you use it immediately?

2. When you use your weapon, do you exhaust your hero and weapon, or just the weapon?

3. When defending, you have to pay to use your weapon correct?

1. Yes, once it is in play.

2. you exhaust your hero after you declare the attack on a target. If your opponent allows the attack to go through, or even if he uses a protector, you then exhaust your weapon.

3. Yes, and your weapon must be ready. Your hero does not have to be.