The path to physical perfection can be attained in many ways. Few exemplify this more than barbarians of the Path of Steelskin, who push beyond their normal limits by learning to temporarily alchemize their skin into metal with nothing but their pure rage. Their hardened skin makes them nearly impervious to any physical attack as blades and spells seem to almost bounce off.
The exact cause of your power may vary. Maybe you can naturally harden your skin from some mutation or maybe you augmented yourself to be able to do this. Regardless, nobody will mess with you now. 

Steelskin

Upon selecting this archetype at level 3, you learn to harden your skin to block attacks, rather than avoid them. Whenever you are not wearing armour, your Armour Class equals 10 + your Strength Modifier + your Constitution modifier + your Dexterity modifier (maximum 2). You cannot use a shield and still gain this benefit.

Blade Block

Starting at level 6, you learn to deflect even the most savage of blows with your hardened skin. While raging, whenever you suffer slashing, piercing, or bludgeoning damage, you may use your reaction to reduce the damage by 1D10 + your Barbarian level + your Constitution modifier.

Kindred Spirits

Beginning at level 10, you can use your action to charm someone with your presence. When you do so, choose one creature that you can see within 30 feet of you. If the creature can see or hear you, it must succeed on a Wisdom saving throw (DC equal to 8 + your proficiency bonus + your Charisma modifier) or be charmed by you until the end of your next turn. While charmed, you may use your bonus action to command the creature to attack a creature of your choice within its movement range. You must finish a long or short rest before you may use this feature again.

Steel Burst

Upon reaching level 14, you learn to harness your defensive powers to also attack enemies. As an action, you may strike the ground, heated steel bursting from the ground around you. Each creature within 30 feet of you must succeed on a Constitution saving throw (DC equal to 8 + your proficiency bonus + your Strength modifier) or take 3D6 fire damage and 3D6 piercing or bludgeoning (your choice) and be knocked prone. A creature that succeeds on its saving throw takes half as much damage and isn’t knocked prone. You must finish a short or long rest before you may use this feature again.