Unarmed, with all three iron fist perk ranks, and with Paralyzing Palm, means that you are king of the universe. That combination is just that powerful. If you use VATS, you get more chances to hit with smaller weapons like spiked knuckles.... with the power fist you get less. Different varieties of power fists are cool, like the Shocker. Stock up on your endurance. You can successfully block, with little damage, when you go outside of VATS. When they recoil, get some good punches in. If they have a projectile weapon, get all up in their faces, and then they freak out and stop firing for a few precious seconds, more whacks for you.