[JimmyPlenty]

5 auto hit
4 negate armor
3 double damage and negate armor

NOTE: negating armor may not mean diddle in light/non armored combat.

or

5 auto hit
4 +1 die damage
3 +2 die damage

NOTE: This still creates triple damage for light weapons, but can be explained by their accuracy. Heavy weapons seem to suffer a small amount though.

or

5 auto hit
4 negate armor
3 negate armor +1 die damage