Pugilist

You are strong. Stronger than weapons and those who use them. Strong enough that body is weapon. When you punch dragon, dragon die, because you are strong.

Fisticuffs

At level 3 you are proficient with improvised weapons. You're base damage die for improvised weapons and unarmed attacks is a d6. This increases to a d8 at 6th level, a d10 at 10th, and a d12 at 14th level. You can make an unarmed attack or improvised weapon attack as a bonus action when you take the attack action with an improvised weapon or unarmed attack. 

Pugilism

At level 6 your unarmed attacks and improvised weapons count as magical for the purpose of overcoming resistance and immunity to non magical attacks and damage.

You now have access to maneuvers. These are used for certain feats. You have a number of maneuvers equal to your rage damage bonus + your constitution modifier per short.

Some feats require a constitution saving throw, the DC is 8 + your proficiency bonus + your strength modifier.

Bob and Weave

When you take damage from a melee attack you can use your reaction to reduce the damage by a d10 + your constitution modifier + your barbarian level. If you reduce the damage to zero you can spend an additional maneuver to gain an opportunity attack with an unarmed attack or improvised weapon against the creature.

Pugilist's Clinch

When you make the attack action with an unarmed attack or an improvised weapon you can spend one maneuver to forgo the bonus action attack for a grapple attempt. You are proficient with this grapple if you aren't proficient in Athletics already. You can spend an additional maneuver to grapple a huge creature.

Stunning Headbutt

At level 14 once per turn, when you make the attack action with an unarmed attack or improvised weapon you can spend one maneuver to attempt a stunning headbutt. The target must make a constitution saving throw or be stunned until the end of your next turn.