OK as pointed out - there are a great many names for various different blades, and I was being a bit to generalistic. I'm not overly familiar with the Zweihänder, I was referring more to the Crusading knight style greatsword - which was what the 'manual' I had seen referred to.
I've had a quick readup on the Zweihänder though. It seems to me that again, I should apologise, when I say 'blunt' I don't mean 'big stick' blunt.
As Andor pointed out 'most' older weapons were not razor sharp, they were sharpened though to allow some cleaving. However I note that the Zweihänder appears to have seen a lot of use as an anti polearm weapon, used to smash through pikes and halbeards - I don't see such a weapon being kept too sharp, simply due to the loss of keeness you'd get bythe time you got to a 'soft' target.
Comepare the Zweihänder two-handed sword to, say, the No-Dachi style weapons of the far east and you get to see different versions of 'sharp'. The No-Dachi (despite how folk would
like to use it) was a massive curved cutting blade ideally used from horseback. Designed to slough away the ranks of chaff from an opposing force, it would have been forged using similar steel folding techniques as a Katana - giving it an incredibly strong cutting edge, yet a flexbile 'spine' (for steel you understand!) meaning your No-Dachi was a serious to gods 6'+ slicing dicing killing machine.
From what I can see the Zweihänder would indeed cut off limbs, heads and cut thy foe in twain - but I bet if you could forensically examine wounds from both blades you'd find a lot more 'tear' with your Zweihänder than that of a No-Dachi. Of course the No-Dachi wasn't quite as effective against other kinds of enemy.
Which is the reason I imagine there are so many different weapons out there - each to fulfill a niche