I’ve been thinking about a simple alternative armor system. As Acritarche pointed out, a flat damage reduction is really powerful: I’d like players who wear heavy armor to feel like there’s a chance their armor won’t protect them. So here it is:
Armor has a value from 1 (thick clothes) to 5 (heavy full-plate armor). When you take damage, roll 1d6. If you roll equal or under your armor value, reduce damage by the amount you rolled. So if you have armor 3 and you roll a 2, reduce damage by 2. On a 3, reduce damage by 3. On a 4, you take the full blow without damage reduction.