Feat: Street Brawler. Please give me your opinion.

The story you can ignore: I have a player who wanted to use the Pugilist class, but after giving the newest one a read, it seems to me that it's kind of a mess I don't want to deal with as a DM. He proposed going for a Barbarian-Monk multi-class, but I know that it would not be fun for him (he doesn't know the rules that well). My compromise for him was to add a few homebrew things to make a Path of the Berserker Barbarian feel like a street punk, and this feat is the central thing for all that.

Let me know if it looks balanced:

Street Brawler

General Feat (Prerequisites: Level 4+, Tavern Brawler)

You gain the following benefits.

Ability Score Increase. Increase your Strength by 1, to a maximum of 20.

Pugilist. Your Unarmed Strike damage is further increased. You deal Bludgeoning damage equal to 1d6 plus your Strength modifier instead of the enhanced damage from Tavern Brawler.

Fisticuff Specialist. When you hit with bladed knuckles, brass knuckles or spiked knuckles, the attack is considered an Unarmed Strike that deals the same type of damage as that weapon.

Knock-Out. When you use the Push benefit of your Tavern Brawler feat, you can force the target to make a Constitution saving throw (DC equals to 8 plus your Strength modifier and Proficiency Bonus). On a failed save, the target receives the Unconscious condition for 1 minute. The condition ends on a target if it takes damage or someone within 5 feet of it takes an action to wake it up.

You can use this benefit a number of times equal to your Proficiency Bonus, and you regain all expended uses when you finish a Long Rest.

Thanks!

Honestly, this seems fine. I'm assuming you have brass knuckle weapons. Note that outside of your setting this feat may not make sense. Also note that 1 minute unconscious is a lot. Otherwise, this is fine. Since you're the DM here, honestly this call is ultimately up to you, but if you're worried it's too strong, consider not linking it to the Push feature. Otherwise your pushing damaging and knocking out. That's honestly too much and kinda doesn't make sense. Make a new feature. Structure it like the push feature and cross referencewoth the sleep spell. Something like:

Knockout. Once per turn when you hit a creature with an Unarmed Strike as part of the Attack action on your turn, you can deal damage to the target and force it to make a Constitution saving throw. (DC 8 + your Proficiency Bonus + your Strength modifier) On a failure the target has the Unconscious condition for 1 minute. The condition end early if the creature takes damage or someone within 5 feet of it takes an action to shake it awake. You can use this benefit a number of times equal to your proficiency bonus. You regain all expended uses when you finish a Long Rest.

That's just a suggestion. Hope it helps. I'd love to hear back from you if it does. No one ever talks back on these quiet threads. It's so lonely out here. 

Edit. Almost forgot to mention. You may want to specify that Fisticuff Specialist does the same damage type AND amount as the weapon. Note that this can be great for monks.

Thanks for your suggestions, I ended up reducing the Unconscious duration:

Street Brawler

General Feat (Prerequisites: Level 4+, Tavern Brawler)

You gain the following benefits.

Ability Score Increase. Increase your Strength or Charisma by 1, to a maximum of 20.

Pugilist. When you hit with bladed knuckles, brass knuckles or spiked knuckles, the weapon’s damage die is a d6 instead of a d4. Additionally, when you roll damage for any of these weapons and get a 1, you can use the Damage Rerolls benefit of your Tavern Brawler feat to reroll it.

Moxie. You can use your Reaction to take the Dodge action.

Knock-Out. When you use the Push benefit of your Tavern Brawler feat, you can force the target to make a Constitution saving throw (DC equals to 8 plus your Strength modifier and Proficiency Bonus). On a failed save, the target receives the Unconscious condition for 1d4 turns. The condition ends on a target if it takes damage or someone within 5 feet of it takes an action to wake it up.

You can use this benefit a number of times equal to your Proficiency Bonus, and you regain all expended uses when you finish a Long Rest.

Also, here's an example of a spiked knuckles weapon:

Spiked Knuckles

Simple Weapon, Melee Weapon

5 SP, 8 oz.
1d4 Piercing
Mastery: Nick

Light. When you take the Attack action on your turn and attack with a Light weapon, you can make one extra attack as a Bonus Action later on the same turn. That extra attack must be made with a different Light weapon, and you don't add your ability modifier to the extra attack's damage unless that modifier is negative. For example, you can attack with a Shortsword in one hand and a Dagger in the other using the Attack action and a Bonus Action, but you don't add your Strength or Dexterity modifier to the damage roll of the Bonus Action unless that modifier is negative.

Mastery: Nick. When you make the extra attack of the Light property, you can make it as part of the Attack action instead of as a Bonus Action. You can make this extra attack only once per turn.