Zweihanders/montantes/whatever you wish to call them were extremely effective and not nearly as heavy as you might think. In general, even the largest swords didn't weigh much more than about three kilograms (and thus were lighter than rifles and some polearms), and the hands were far enough apart that you had enough leverage to move quickly. If you poke around on youtube for people sparring with such weapons you'll see that they're as quick as most other swords (and have an advantage in reach).

On the article itself, while it's a nice list, it perpetuates some myths about the weapons in question (e.g. that katana was in someway superior to western swords -- high quality specimens on either side would probably be pretty closely matched), and has some fairly glaring admissions (e.g. the yari (Japanese spear) which was one of the most common weapons among footsoldiers for a good deal of Japan's history).