I make a lot of monkey fist self defense tools. I make them as discreet carry bracelets, and long flails and as I will show here as lanyards. You could use this for a knife lanyard, or attach it to your keys or what not. Like most of my monkey fists, this one contains a 5/8" stainless steel ball bearing.
Here we have it as a lanyrad on my trusty Cold Steel AK-47
Here it is on my key chain. Also visible is my two bight turks head key fob.
This is an older photo, of the same lanyard minus the skull bead on one of my nicer carabiners.