All weapons should have a chance of crushthrough based on their weight, speed/physics effects, the wielder's str, the blocking weapon's weight, and the foe's str. Most of the time, weapons would not crushthtrough, and blocking would go as normally, but a great bardiche against a short sword would not go well for the swordman. Also, thrusting a lance/spear from horseback would often go through an opposing downblock due to the speed/force behind the thrust.
A complementary idea would be if simply clicking attack/block was less powerful/resistant than holding the button longer. This, way the players would have more control over the prevention of crushthrough, or its execution.
The great maul should perhaps be limited to overhead swings, although that is a bit extreme