OB1
Jedi Master
So I've considered some of the feedback presented and have adjusted the archetype accordingly.
Hulk Smash
Starting when you choose this path at 3rd level, your fists become brutal weapons, becoming larger with sharp, bony protrusions growing from the knuckles. Your unarmed attacks now deal 1d6 bludgeoning damage. If you are not carrying weapons or using a shield, your unarmed attacks add double your rage damage while raging.
Based on average damage, I calculate that the difference between the unarmed strike and a greatsword is 1 point (in favor of the greatsword). This assumes that the Barbarian of the Hulk is raging, not using a shield and gaining double rage damage with a 16 strength against a non-Hulk raging barbarian with 16 strength using a greatsword. By level 20, the difference changes in that based on average damage the unarmed Hulk Barbarian is better by 1 point. Unarmed damage will be more consistent, but barbarians using weapons will have higher damage potential and have better damage dice to use for Brutal Critical.
Hulk Bash
Beginning at 3rd level, when you enter rage you grow more massive and your muscles bulge. Regardless of your starting size, you become large. Barbarians of the Hulk that are already large sized grow one size category larger (included just in case a large sized player race is ever created). If there isn’t enough room for you to grow to your new size, you attain the maximum possible size in the space available. As a result of your new size and strength, while raging you deal an additional 1d4 damage when you successfully strike with a melee attack. This damage is of the same type as made by the melee attack.
Prodigious Leap
Beginning at 6th level, you can leap much farther than normal. You normal jump distance is doubled. While raging, your normal jump distance is tripled.
Reasoning: It was suggested, and I liked it. Seems consistent in power level with other 6th level barbarian archetype abilities.
I got thinking about alter self and how that spell mirrors some of the bony-protrusion descriptions you are going after here. Going with that, I thought maybe reorganize this a bit.
3rd Level
Gain the Slam attack - 2d4 + Str
Gain Tavern Brawler abilities - Unarmed Strike 1d4, Proficient with Improvised Weapons, Hit with unarmed, bonus action grapple
Rage - Grow to Large, gain 1d4 to all unarmed attacks + Rage, Slam attack becomes 3d4 + Str + 2xRage
6th Level
similar to the alter self spell, your fists grow bony protrusions and become +1 Magical weapons when raging
You're jump distance triples when raging
So when you rage, you can either Attack and Bonus to get 2d4 + STR + Rage and 2d4 + Rage (17dmg), or Slam attack to get 3d4+Str+2xRage (15dmg) and bonus to grapple. At higher levels Slam will start to outpace two unarmed strikes due to the rage bonus. This also makes your unarmed strikes magical at the same level as Monks, which is needed. The Slam attack is also better than a great axe when raging and keeps up even with GWM at higher levels.