Dynamic Laminar Device

A simple device, that seems obvious to everyone once its been discovered. Made of a couple of laminate sheets of an elastic polymer, whose fibres are known to contract when subjected to a specific activation energy. Variants have been constructed that respond to electrical fields or certain types of radiation; although the original product in the range (usually known by its trademark name: Combat Training DLD) is activated by a combination of kinetic energy and a weak electrical field, sufficient to be set off by the static charge a person usually gets by walking around.

These were originally created for fencing practise. The weapon is a practise sword whose blade is a 2 or 3 foot length of soft DL material, normally having the consistency of foam rubber. When a person is struck, the elastic layers produce a distinctive boing sound, and after approximately a half second the shaft becomes straight and rigid. This means that striking someone is unlikely to bruise, but it is easy to tell when a blow has landed. The force of the chemical change can also knock a person off balance, although it isn't sudden enough to cause concussion or many other complications.