I should point out that most one-handed swords (steel and bronze) way no more than about a kilogram. Five pounds is reasonable for a two-handed weapon, but that's not what is shown. As for the video, he's not the first to reproduce the Maciejowski glaive. Museum Replicas had an edition about a decade ago, and it was judged extremely awkward and tip heavy.
The point here is that when most warriors go for kilogram-scale single-handed weapons, regardless of culture, regardless even of metal used, a double-weight weapon doesn't immediately jump out as a massive improvement
Just to dump some more sand in the gears, I'd like to point out that the plow (pflug) is one of the fundamental stances in European sword fighting, one that probably will look very familiar (
http://www.thearma.org/essays/StancesIntro.htm). If a swordsman says "the Plow" is his favorite and he's killed many men with it, what's an artist to make of that? Paint a warrior with a plowshare in his hand, perhaps?
Best,
F