Mercurial Sword
An illegal weapon constructed by Roger Shrubstaff to test a theory about the inefficiency of a fantasy sword from Dungeons & Dragons (actually originally from the Book of the New Sun).
The idea in the fantasy setting was that the sword would contain a hollow tube running down the middle of the blade, into which a length of mercury would be inserted, which would supposedly swing out to the end and provide greater force upon the hit (to the tune of one die type larger, 1d6->1d8, 1d8->1d12 and so on). The amtgard version of this sword used a thick PVC core with threaded ends, a metal weight about 4" cylinder with springs welded onto either end, and springs affixed to pvc threaded pvc caps by way of a "metal putty", and the entire contents of a can of WD-40 emptied into the tube so the weight could slide easily. This entire assembly was then placed as the core of a standard funnoodle and covered in cloth.
As Oznog predicted, the claims of the weapon's greater force are crap. He correctly noted you would need to use more force to swing the weapon to propel the weight from the hilt to the tip. If the weight started at the top, it then had some additional mass, but it would have been easier to just have a permanent weight at the tip. The spring caps did prove effective in keeping the weight from breaking out however.
The sword was eventually given to Auwyne as a gift. What became of it after that I have no idea.
Modifications
The weapon was designed to allow various weights to be subbed in when the cap in the hilt was removed. Glenalth suggested using graphite powder instead of a single metal weight. This might have worked better if the tube wasn't already filled with WD-40.
