Ambusher. In the first round of a combat, the bandit fighter has advantage on attack rolls against any creature it surprised.

Sand Pouch. The bandit fighter carries a small pouch of sand for use in combat.  The pouch has three uses.

Second Wind.  The bandit fighter has a limited well of stamina that it can draw on to protect itself from harm. On its turn, the bandit can use a bonus action to regain hit points equal to 1d10 + 4. Once it uses this feature, the bandit must finish a short or long rest before it can use it again.

Athlete.  The bandit fighter's Strength is increased by 1 (already calculated), to a maximum of 20. When it is prone, standing up uses only 5 feet of the bandit's movement.  Climbing doesn't cost the bandit extra movement. The bandit can make a running long jump or a running high jump after moving only 5 feet on foot, rather than 10 feet.

Multiattack. The bandit has two attacks with its longsword or one with its sand spray and one with its longsword.

Longsword. Melee Weapon Attack: +3 to hit, reach 5 ft., one target. Hit: 7 (1d8 + 3) piercing damage.  Versatile: +3 to hit, reach 10 ft., one target. Hit: 9 (1d10 + 3) piercing damage. 

Sand Spray. Ranged Attack: +2 to hit, reach 5 ft., one target. Hit: The target is considered blinded for one round.

Disarming Strike.  When the bandit fighter hits a creature with a weapon attack, it can expend one superiority die to attempt to disarm the target, forcing it to drop one item of your choice that it’s holding. You add the superiority die to the attack’s damage roll, and the target must make a Strength saving throw. On a failed save, it drops the object you choose. The object lands at its feet.

Maneuvering Attack.  When the bandit fighter hits a creature with a weapon attack, it can expend one superiority die to maneuver one of its comrades into a more advantageous position.  Add the superiority die to the attack’s damage roll, and the bandit chooses a friendly creature who can see or hear it. That creature can use its reaction to move up to half its speed without provoking opportunity attacks from the target of the bandit fighter's attack.

Riposte.  When a creature misses the bandit fighter with a melee attack, the bandit can use its reaction and expend one superiority die to make a melee weapon attack against the creature. If the bandit hits, it adds the superiority die to the attack’s damage roll.

Sand Spray.  When a creature within 5 feet of the bandit fighter makes a melee attack, it can use its reaction to throw a fist full of sand in the face of the attacker.  The attacking creature must succeed a DC 15 Dexterity saving throw, or be blinded for one round.   Any creature sized huge, or larger, has advantage on this saving throw.