@Dwarf: My apologies. I meant the physical location of the extra weight was the pommel. The cross-guard would then be the center of gravity, as you've stated. The point stands that a standard infantry sword has a center of gravity that wasn't a good 5-6 inches past the wrist of the wielder. As far as a war-axe, you're going to have two basic sorts of axes used in combat. Light, slashing weapons that are also balanced for throwing, or fat limb loppers that crash into your opponent, relying on weight to sunder an opponents armor. Dwarves being dwarves, I'm assuming that the axes in DF are the later category, but I suppose I could be wrong.
Frankly, I'm not so sure any organized military ever actually used the second type, but not that many bothered with the first type either. The reality is that once you start talking about a weapon shaped like an axe and balanced like a sword, you're talking about a weapon that is clearly and completely inferior to a sword, with the caveat that they are great throwing weapons. Other than throwing, there is no -point- to having an axe with an even weight distribution. It's incredibly difficult to parry with an axe, it's an awkward shape, its striking surface is limited, and you can't stab with it. You have to have some kind of benefit in exchanging all the utility that a sword gives you. A top-heavy weapon with a great deal of leverage gives you something that the sword doesn't bring to the field. Also, if the DF axes weren't top-heavy, they'd be no better at lopping off limbs than a sword, and they would be completely useless for chopping wood.