(Adapted to a Fighter sub-class from a homebrew class I designed. The class was designed to fit in a campaign where firearms were quite common.)

Antiquarian

A half-elf moves with elegant grace, her light blue robe flutters softly in the wind. The blade in her hand seems to dance as it cuts deftly through the leaves that float down from the canopy above.

A male halfling leaps into the fray, the links of his chain shirt clinking together as his dagger cuts into his foe. His opponent strikes back, but the halfling has danced away out of reach. Running, leaping, and striking, the halfling winds his way through the battle.

A human swings his staff against the target dummy before him, strands of yellow ribbon stream from the end as it arcs through the air to land with a heavy thud. Despite its foundations buried in the ground, the dummy shakes with each thunderous blow.

For some, the time of conventional weaponry has long passed, its teachings now archaic. For antiquarians, the beauty and peace that can be found in those teachings is above all else. Some fight for the thrill of battle, others for the glory and reward, but all antiquarians fight to share this beauty with others.

A Life of Beauty

Antiquarians are as rare and exotic as the scrolls that maintain their traditions, and are commonly alone in their studies. Small gatherings may train together but these groups of antiquarians are incredibly rare and are often treated with disregard by its community, at best, and shunned, at worst.

Though differing in temperament and personality, all antiquarians are struck by the stark contrast between the world in which they live and the forms they practice. Where the society that surrounds them might be filled with malaise and strife, antiquarians find beauty in the stroke of a sword. Where life on their planet may be harsh and cruel, their techniques shift and flow until it is almost a dance, soft and delightful. This often causes antiquarians to look for beauty in other ways, turning to a life filled with creativity and the arts.

Proper Technique

Starting when you choose this archetype at 3rd level, you gain a +1 bonus to damage on attacks you make with a melee weapon. This bonus increases to a +2 when wielding a two-handed weapon.

These bonuses increase by +1 at levels 7, 12, and 15, +2 for two-handed weapons.

Cover to Cover

Also at 3rd level, you have learned to use the environment around you to your advantage. On your turn, if a Dash action would allow you to reach a position that would grant you at least half-cover, you can take the Dash action as a bonus action.

At 7th level, difficult terrain no longer impedes your movement and opportunity attacks against you caused by movement are at a disadvantage.

At 15th level, you have learned to use your cover to maximum effect. You gain a +2 bonus to AC when behind cover. This bonus is in addition to the bonus to AC provided by cover.

Fluid Movement

At 7th level, you can use your reaction to deflect a melee attack that hits you, reducing the damage by 1d8 + your Dexterity modifier + half your Fighter level.

If you reduce the damage to 0, you can attempt to disarm the target. The target must make a Strength saving throw, using the number you rolled as the DC. On a failed save, the weapon drops at the target’s feet. If you have a free hand, you can instead attempt to grapple the target.

Maximized Critical

Starting at 10th level, when you score a critical hit with a melee weapon you treat the lowest damage die result as the maximum result.

At 15th level, your critical hits now deal triple damage.

Dance of Forgotten Days

Starting at 15th level, you can spend your action to make a Performance check. All hostile creatures within 30’ that can see you must make a Wisdom saving throw against a DC equal to your Fighter level + your Dexterity modifier. On a failed save, a creature is frightened of you for 1 minute. At the end of each of its turns, a creature can attempt to save from this effect. On a successful save, this ability does not affect that creature. Once you use this ability, it can’t be used again until you have completed a short rest.

Circle of Strikes

Starting at 18th level, you can spend an action to make two melee attacks against a number of enemy creatures you choose within your weapon’s reach, up to your Wisdom modifier. Once you use this ability, you can’t use it again until you finish a long rest.