Pugilist

Martial Archetype
Comment from the Palm: A variation on the Monk/Fighter, this one mostly just focuses on punching things really, REALLY hard. While not intended to be a conversion of the class from FF 14, it would certainly work as such. Also, yes, it’s intended that you can use a shield with Close Quarters Combat, as I want a way to natively play Captain America. 
     Don’t judge me. (Quick comment from the Finger: No judgement here; I wrote shield expert to scratch the same itch.)

Pugilist

Conventional thought states that a warrior is only as good as his weapon. For a pugilist, his weapon and his hands are one and the same. Though intense physical conditioning, a pugilist strives to forge his body into the ultimate tool of war, without relying on magic or the mystical crutch of Ki.

Close Quarters Combat
Starting when you choose this archetype at 3rd level, your study of unarmed fighting grants you mastery of combat styles utilizing such techniques. You gain the following benefits when you aren’t wearing medium or heavy armor or using a shield:

• You can use your Dexterity instead of Strength for attack and damage rolls of your unarmed strikes, and you can use your Strength instead of Dexterity for determining your AC.
• When you take the attack action on your turn, you can use a bonus action to attempt to grapple a creature within your reach.
• Your unarmed strikes and fist weapons deal 1d4 damage, and deal increased damage as you gain levels in the fighter class, as shown below:

• • 7th level    1d6 
  • 10th level  1d8 
  • 15th level  1d10 
  • 18th level  1d12 

Close Quarters Fighting Styles
At 3rd level, you learn to utilize your traditional combat training in unique ways, granting you a measure of flexibility better suited to your chosen path. Your chosen Fighting Style changes in the following ways when you aren’t wearing medium armor, heavy armor, and aren’t using a shield:
     Defense. You gain an additional +1 to your AC, for a total of +2, and you gain this bonus even if you are not wearing armor.
     Dueling. Your unarmed strikes deal +2 damage. You are treated as if you are wielding a one-handed finesse weapon for the purposes of feats and other class abilities.
     Great Weapon Fighting. When rolling damage for an unarmed strike, you can reroll any 1s or 2s. You must keep the new result, even if it is a 1 or 2. You can treat unarmed strikes as attacks with two-handed heavy weapons for the purposes of feats and other class abilities.
     Protection. You gain the benefits of Close Quarters Combat and Close Quarters Fighting Style while using a shield. When you take the attack action on your turn, you can use a bonus action to make an additional attack with the shield you are wielding, which deals 1d4 bludgeoning damage.
     Two-Weapon Fighting. When you take the Attack action on your turn, you can make an additional unarmed strike as a bonus action. You are treated as if you are wielding two one-handed light weapons for purposes of feats and other class abilities.
     Additionally, as an action on your turn, you can choose to replace any of your current fighting styles with a different fighting style, though you still cannot benefit from the same style more than once. Starting at 7th level, you can replace your fighting style/styles as a bonus action instead of an action. 

Intensive Training
At 7th level, your training has given you an edge in all physical contests. Add half your proficiency modifier to all Strength, Dexterity, and Constitution checks that you do not already add your proficiency modifier to. Additionally, you can select either Athletics or Acrobatics: you gain proficiency in this skill, or double it if you already had proficiency.

Knockout Blow
At 10th level, you have learned to channel your impressive physical power into a single, devastating blow. When you use the Attack action on your turn to make an unarmed strike, you can forgo any additional attacks you gain from the Extra Attack feature. For each attack you would give up in this way, you can add two additional damage dice to your unarmed damage roll, and the attack is treated as magical for the purposes of bypassing damage resistance and immunity. You must choose to use this ability before the attack is rolled.

Close Quarters Master
At 15th level, you’ve become a true master of unarmed combat. You learn an additional Fighting Style, and you have advantage on grappling checks against creatures of your size or smaller. Additionally, you can attempt to grapple creatures two size categories larger than yourself.

Focused Offense
Starting at 18th level, once per turn when you deal damage to a creature with an unarmed strike, you can heighten your awareness of their attacks. You gain resistance to any damage that creature deals to you until the beginning of your next turn.

New Weapons

Cestus. A cestus can take many shapes, but in all cases it is comprised of some sort of glove or hand wrapping covered with metal, stone, bone, or some other hard, blunt material, normally worn in pairs. Unarmed fighters often use them simply to protect their hands, but they are also useful for covering in special materials, such as silver or alchemist’s fire. Wearing a cestus allows your unarmed strikes to deal 1d4 points of bludgeoning damage.
     Claw gauntlet. Claw gauntlets take two general forms: either a gauntlet with one to three long, sharp claws extending from the top of the arm to approximately one foot past the end of the wearer’s fist, or a glove/gauntlet with sharp metal talons extending from the ends of the fingertips. In either case, they serve to slice the wearer’s opponents to ribbons. Wearing a claw gauntlet allows your unarmed strikes to deal 1d4 points of slashing damage.
     Punching dagger. This unique style of dagger consists of one or more blades attached to an H-framed handle, allowing a proficient user to augment his unarmed strikes. Wielding a punching dagger allows your unarmed strikes to deal 1d4 points of piercing damage.

New Weapon Property

     Fist. You can treat attacks with this weapon as unarmed strikes.

Changelog:
4/15/17 Multiple balance changes:
 – You can now use either Strength or Dexterity to determine their AC when wearing Light or no armor.
 – Knockout Blow is treated as Magical for purposes of overcoming damage resistance and immunity.
8/9/17: Added in 7th level ability to swap fighting styles as a bonus action. Changed Defensive CQC ability.
Deadblow: Replaced by Focused Offense