I can see this going either way. The rules state:
This weapon deals 5 fewer damage unless the target is wearing no armor or archaic armor. Archaic weapons are made of primitive materials such as wood or common steel.
So if you score a crit with an archaic weapon against armor do you subtract -5 to the total damage or -10? Thanks.
Well, given how you usually apply bonuses before multiplication, it'd stand to reason you'd apply penalties before multiplication aswell. If your extra damage from strength bonus gets doubled on a crit, it makes sense for the penalty to get doubled too.
However, if I was running the game, I'd likely go with Voss' idea and not diminish the crit quite that much. I'm just not convinced that's entirely in line with the rules as written.