[PapaBear3625]

The vest was my first thought. But also the opposite -- some science fiction discusses a weapon created through a mono-molecular sword. It's basically a strong, impossibly thin weapon which simply slices through anything at all.

Larry Niven had stuff like that in several stories. Stiffened by a force field, it's a sword. Flexible, it can be used to cut through things if you have a handle on each end (or a weight on one end which allows you to swing it).

[Toddsterpatriot]

It’s fun to play with until someone gets their head cut off.