Why not stick them hard and slice them again when you pull it out? One thing I feel DnD 5e might miss is degrees of success. Let’s build into that!
When you are wielding a piercing weapon, you hit with a melee attack roll, and hit 5 greater than the targets AC, you can elect to run through the target sticking the target with your weapon. If you do, when you next make an attack, you can pull your weapon free dealing damage as if you had just struck the target without requiring an attack roll. This automatic damage is as if you had successfully hit the target, but not critically hit he target.