Some fighters specialize in multiple weapons. Others are practitioners of the bow. And then, there are those who develop a kinship with a single weapon, that chosen weapon becoming an extension of the fighter itself.

As an ancient weapon master, you have selected a weapon to develop a bond with. Through your travels, you and the chosen weapon grow as one. In time, it is less a weapon, and more a partner; perhaps it is even like family.

Bonus Proficiencies

When you choose this archetype at 3rd level, you gain proficiency with the History skill and smith’s tools.

Chosen Weapon

When you select this archetype at 3rd level, you can attune to a weapon of your choice, making it your chosen weapon. To do so, you must conduct an hour-long ritual that binds you to that weapon. Once the hour ends, the chosen weapon takes on a dull blue glow, emitting dim light in a 10-foot sphere. As a bonus action, you can deactivate or reactivate this light.

While you are away from your chosen weapon, you can use an action to sense the direction of your weapon, as long as the weapon is on the same plane of existence as you. If the weapon is in motion, you know the direction of its movement. This effect can’t locate your weapon if any thickness of lead, even a thin sheet, blocks a direct path between you and your weapon.

Any creature other than you that makes an attack with your chosen weapon does so with disadvantage.

You may only have one chosen weapon at a time. If you perform this ritual again on another weapon, the chosen weapon status of the first weapon is removed and reapplied to the new weapon.

Martial Symbiosis

As a bonus action on your turn, you can empower your chosen weapon. While empowered, your chosen weapon deals an additional 1d4 damage on a hit. In addition, you also gain a +1 bonus to your AC.

The bonus to your AC increases when you reach certain levels in this class, increasing to +2 at 10th level, and +3 at 15th level. These effects last until the start of your next turn.

You can use this feature three times, and you regain all expended uses of it when you finish a long rest.

Magical Awakening

Starting at 7th level, unless it is already a magical weapon, your chosen weapon counts as magical for the purpose of overcoming resistance and immunity to nonmagical attacks and damage. In addition, you gain one of the following benefits of your choice.:

Dispelling Strike

Immediately after you use the Attack action on your turn and successfully hit a creature or object with your chosen weapon, you can end the effect of any spell of 3rd level or lower on the target.

Once you use this feature, you can’t use it again until you finish a long rest.

Mind of its Own

As an action, you can imbue your chosen weapon with temporary sentience which lasts for 1 minute. While sentient, your chosen weapon gains a flying speed of 20 feet. On each of your turns, including the turn you grant its sentience, you can use your bonus action to telepathically move the chosen weapon and attack a creature within reach or range of it. This effect also extends to any ammunition used by the chosen weapon which follows it.

While your chosen weapon acts on its own, it does not add your Strength or Dexterity modifier to its damage rolls. Furthermore, your chosen weapon must remain within 20 feet of you, or it loses its sentience, and if it is flying it immediately falls to the ground. At the end of the duration, your chosen weapon immediately returns to your hand unless it is prevented from doing so.

Once you use this feature, you can’t use it again until you finish a long rest.

Out of Sight

As an action on your turn, you can turn invisible as long as you are carrying your chosen weapon. This invisibility lasts for 1 minute, or until you attack or cast a spell.

Once you use this feature, you can’t use it again until you finish a long rest.

Unbreakable Bond

Starting at 10th level, when you roll initiative and have no uses of Martial Symbiosis remaining, you regain one use.

Ferocious Strike

Starting at 15th level, the attacks you make with your chosen weapon have the potential of disorienting your targets. When you hit a creature with an attack using your chosen weapon, that target must succeed on a Wisdom saving throw (DC 8 + your proficiency bonus + your Strength modifier) or the target has disadvantage on its attack rolls until the end of your next turn. If the creature succeeds on its saving throw or the effect ends for it, it is immune to this effect for 24 hours.

You can use this feature only once on each of your turns.

Legendary Weapon

At 18th level, you gain one of the following features of your choice:

 

Avatar of Destruction

While you are wielding your chosen weapon, as a bonus action on your turn you can transform into an Avatar of Destruction. You take on a fearsome appearance, which gives you advantage on Charisma (Intimidation) checks.

Additionally, you gain a fly speed of 30 feet. If you fly and dive at least 30 feet straight toward a target and then hit it with your chosen weapon, the attack deals an extra 2d6 damage to the target. This effect lasts for 1 minute or until you use your bonus action to dismiss it. 

Once you use this feature, you can’t use it again until you finish a long rest.

Ghostwalk

While you are wielding your chosen weapon, as a bonus action on your turn you become incorporeal and can teleport up to 60 feet to an unoccupied space that you can see. In your incorporeal state, you gain immunity to bludgeoning, piercing, and slashing damage from nonmagical attacks and you have advantage on Dexterity saving throws. Other objects and creature can move through you as if you were difficult terrain. You remain incorporeal until the start of your next turn or until you move or take an action or reaction.

Once you use this feature, you can’t use it again until you finish a long rest.

Legendary Radiance

As a bonus action on your turn, you can cause your chosen weapon to glow with radiant energy. Your weapon casts bright light in a 30-foot radius sphere and dim light for an additional 30 feet. While your chosen weapon glows, undead and fiends have disadvantage on their saving throws and invisible creatures become visible within 30 feet of you. If you hit a creature with your chosen weapon while it is glowing, it deals an extra 1d6 radiant damage. This effect lasts for 1 minute or until you use your bonus action to dismiss it.

Once you use this feature, you can’t use it again until you finish a long rest.