How about hurting your opponents so they can’t hurt you in a Fighting Style?
When you make an attack, you can cause your opponent to have to make a Constitution Saving Throw equal to 8+proficiency+strength or dexterity modifier (whatever you used for the attack). If the target fails, they gain a -1 penalty to their attack rolls. These penalties are cumulative, but may never be larger then your proficiency bonus. As an example, at level two the maximum penalty you can inflict to attack for a target is a -2 as your proficiency bonus is a +2.