I don't use the maths, but here's a simpler solution for you:
Cut has the highest damage of all weapons, but also both the greatest reduction and soak factor. As such, it deals the lowest damage against armor, relatively speaking.
Pierce has the lowest reduction factor and a mediocre soak factor. This means that piercing weapons penetrate armor easily, but still suffer from quite a lot of soak factor. As such, you will glance the least often with piercing weapons, giving you a rather consistent damage output.
Blunt has the lowest soak factor and a mediocre reduction factor. This means that blunt weapons will glance more often on armor than pierce (Not as much as cut though), but once it "breaks" through the armor, it deals a lot of damage. This is invented to make some blunt weapons effective against armor, and others not.
For example: Staffs and mauls both have blunt damage type. One would then think both would be good against armor. This is not the case.
The staff deals so little damage that in most cases it will glance off, never "breaking" the reduction or just barely.
The maul, on the other hand, is great against armor. Its damage is so high it has no troubles getting through the reduction, and once it "breaks" through, it has a very low soak factor.
TL:DR: Both pierce and blunt are good against armor, as long as you are not using a low-damage blunt weapon.