If you read fantasy or history, you may be interested in this article on What Did Historical Swords Weigh?

From ordinary hands-on experience we know full well that swords were not excessively heavy nor did they weigh 10 or 15 pounds and more. There is only so many ways we can repeat how these weapons were not at all heavy or ungainly. Remarkably, while one would think a crucial piece of information as the weight of swords would be of great interest to arms curators and arms historians, there is no major reference book that actually lists the weights of different types. Perhaps this vacuum of documented evidence is part of the very problem surrounding the issue. However, there are a few respected sources that do give some valuable statistics. For example, the lengthy catalog of swords from the famed Wallace Collection Museum in London readily lists dozens of fine specimens among which it is difficult to find any weighing in excess of 4 pounds. Indeed, the majority of specimens, from arming swords to two-handers to rapiers, weigh much less than three pounds.

Despite frequent claims to the contrary, Medieval swords were indeed light, manageable, and on average weighed less than four pounds.

(via A Sweet Familar Dissonance)