Here is something I tied up last night. Had some thoughts in my head since doing the recent video Paracordist Impact Weapons, Paracord Monkeys Fists VS. Blackjacks and Saps (http://youtu.be/rBzXHzpfIlk). Decided to get a prototype going. Here's how it works, briefly:
Draw the keys and paracord monkeys fist in close to the spring loaded, turks head covered handle (made and transfered quite easily with the Perfect Turks Head Mandrel / Jig (http://www.paracordist.com/perfect-turks-head-mandrel-jig/). Next, insert thumb and wrap lanyard securely around wrist and voila - blackjack!
....Or draw the handle back along the 550 cord to the opposite end of the keys and monkey fist and you have a paracord Mace!
I've found that the wrap-around nature of the turks head brings tremendous stiffness to the spring. The spring size and stiffness used in this prototype is thus major overkill; to the extent that much of the desired spring is gone. In my next evolution I'll use a smaller diameter spring.