I can guarantee you that the actual sword did not weigh anywhere near 30 pounds. Swords of that size usually weigh in the neighborhood of 4 to 6 pounds. It would take a large, strong man to wield it effectively. A soldier trained in the use of such a weapon would be able to swing it with amazing speed and devastating impact. The replica may well weigh 30 pounds as many people who make replicas have no idea of what real swords used in the middle ages actually weighed. Anyone who tried to use a 30 pound sword in combat would have been quickly cut to pieces.
Anyone interested in the characteristics and handling of real medieval and renaissance swords should check out the Association for Renaissance Martial Arts. There is lots of data at their web site.
Wallace's sword (the actual sword) which is on display in Scotland weighs 6 pounds.
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