This is the best suggestion I've seen to solve the problem:
If you roll under 10 - Complete miss
If you roll over base but under dex - they dodge out of way
If you roll over base/dex but under armour - glancing blow(no damage)
If you roll over base/dex/armour but under shield - they block it away with shield
If you roll over total AC thats a hit(with damage)
Make animations based on this.