Lanyards can help you to keep your grip on a knife in many different ways.

It can help your knife work as a better chopper by extending your chopping radius by a couple of inches. On the other end, it can help you choke up on the knife for more fine work closer to the tip.

If you are in a situation where you want to use a lanyard and still be able to release the knife, instead of putting your hand into the lanyard loop and securing it to your wrist, you can use it like a strap, secured to your thumb.