Okay, let's just say this is a hypothetical situation. You have the perfect amount of strength to pierce and cut through human bone and flesh with ease. Alright.

If you stab them with a spear or sword, stabbing motion. You're thrusting it into them, and probably out the back. BUT, once the flesh meets the hilt, the forward movement stops. Because it has nowhere to go.

NOW

If you swing your blade in a slicing motion, axe/sword/halberd/whatever, your blade has nowhere to stop if you can go clean through them. So if you swing it, it'll cleave them in two. And it won't stop until you make it stop.