[*]Give the weapon a penetration and a damage die. Targets would only absorb up to a certain number of penetration units (say: 3 for a human or 6 for a large creature). Armour absorbed penetration units. For example, if a weapon had a penetration of 6 and a damage of 1D6+1, it would do 3D6+3 to an unarmoured character or 1D6+1 to a character with armour value 5. Everything else would carry on out the other side, perhaps also damaging items behind the target.
I have to admit it took me a couple of go arounds to Grok this option. It's kinda amusing. It's on the list to see how it works for vehicles as well.
Right now the idea that has caught is rating a weapons damage in Penetration and wounding dice, All rolled together with the total used for armor penetration and only the wounding dice for damage.
A thought occurs while I am writing this shouldn't reflec provide some protection vs plasma weapons as well?