One of my swords is quite interesting from the "armour piercing" perspective; it's an
Albion Kingmaker which has what is effectively a strengthening rib down both sides of the blade instead of the usual fuller. I mean it is fullered to reduce weight but what're effectively double fullers, one running each side of that spine, so that sectionally the blade is a sort of flattened diamond shape with concave edges. The result is a much stiffer blade than it might otherwise have, and as you can see from the link, it's also very pointy. But I dare say it would still take a lot of strength to shove it through plate armour if a vulnerable spot wasn't found.
I was speaking to someone local who makes crossbows (I mean for reenactors, film studios and so on) and he had this really big bastard with a winch. He demonstrated it to me; in fact he was going to let me have a go, which is probably a bad idea anyway, but it was unfinished and needed some adjustments so fired it himself. Certainly looked pretty scary, but he said that for all the winding, the noise and the very visible violence it inflicted on its target, the bolt was only about as powerful as a .22 bullet. I guess due to the speed difference it had a fair bit more momentum, but it put it into perspective.