We (along with many others) call the outside edge of the hand (pinky side) the “blade”. It’s a funny name for something so dull but in many instances, this edge of the hand can be used to cut… sort of.
When doing a standing armbar, it is often easier to roll the triceps by cutting with the blade of the hand rather than a fist. In many wrist locks, a student often creates a cutting force on their partner using the blade of the hand.
The hand is a versatile tool, not only for striking but also for pushing. Experiment with the blade of the hand versus grabbing or even using a fist when you apply various locks and see what kind of results you get. As with all drills, start by doing it in the air, then on a non resisting partner and then finally begin to add some resistance.