No Such Thing

You know that there is no such thing as fighting honorably or well. There is only surviving, and you do anything you must to survive. When you take this feat, pick one of the following options.

1. Fist full of sand: As a bonus action, you can attempt to blind an enemy within 5 feet of you. The enemy must succeed on a DEX saving throw (DC 10+your Slight of Hand modifier), or become blinded until the end of your next turn. You can use this ability a number of times equal to your proficiency bonus per long rest before you must restock on sand.
2. Headbutt: When an enemy within 5 feet of you makes a melee attack against you and misses, you may use your reaction to headbutt them. You deal 1d6+STR damage to the enemy, and they must succeed on a CON saving throw (DC 8+your Athletics modifier) or become stunned until the end of their turn. If you enemy succeeds, you take 1d4 damage instead.
3. Prone Fighting: If an enemy within 5 feet of you knocks you prone, you may use your reaction to choose if they must succeed a DEX or STR contest with you. If they fail, they also fall prone and are grappled by you. While both you and your target are prone you have advantage on any melee or touch spell attack rolls and grapple checks against the prone enemy. 
4. Twist the Knife: You may use your action to attempt to wound an enemy below maximum HP. When you successfully make a weapon attack roll against an enemy, you can use your reaction to force them to make a CON saving throw (DC 10+Athletics modifier). On a fail, they are unable to regain hit points until the start of your next turn.
5. Sock full of Coins: You never fight with just your hands. You become proficient with improvised weapons and they now deal 2d4+STR damage. After you successfully land an unarmed or improvised weapon attack, you can pull out and make an attack roll with a Sock Full of Coins as an improvised weapon. This attack deals 2d6+STR damage and can only be used once per turn.