Arthur

Arthur is a weapon that responds to the wielder's good spirit and nature. Bringing out their true potential for greatness. Slumbering within the blade are souls of 15 Knights who have sworn their souls to Arthur. Once a wielder is chosen, no other creature may attune or wield it until the death of it's current wielder. Forever vigilant, Arthur warns you of danger. While Arthur is on your person you and any of your companions within 30 feet of you can’t be surprised, except when incapacitated by something other than nonmagical sleep. Arthur magically awakens you and your companions within range if any of you are sleeping naturally when combat begins.

Knights of the Round: The order of appearance when using Camelot and the order of names expended by Excalibur.
Lancelot, Gawain, Galahad, Geraint, Gareth, Gaheris, Bedivere, Ector, Kay, Dagonet, Lamorak, Tristan, Percival, Agravain, Bors. 

You gain a +3  bonus to attack and damage rolls made with this magic weapon. This weapon deals radiant damage and If attacking a creature resistant or Immune to Radiant damage, the sword deals magical slashing instead. The sword holds 15 charges of the Knights of the Round.

If you roll a 20 on the 1d20 attack die with Arthur, you can restore one charge of Knights of the Round ability. You can also, as a bonus action, Disengage, provided you have No Charges Left (Knights of the Round Charges Restored in the order of the Names listed, If a name has not been expended, the charge jumps to the nearest expended name). Charges restored are always in the order of the Knights of the Round.

Excalibur. You can expend, 1 or up to 15, charges to deal an extra 1d8 radiant damage, per charge, on your next attack, as you summon the Knights of the Round to strike with you. Once a charge is expended, it can only be restored with the previously stated ability, one charge at a time. It recharges all charges daily at dawn. You can still Summon the Ethereal Knights, provided you have at least 1 charge left (Summoned in Order of the Names Listed provided a blade). Should the creature be resistant or immune to the radiant, it deals magical slashing instead. 

All Hail the King. While attuned to Arthur, you can cast the Command Spell at 1st Level, DC 18, 3 times per day. All charges are restored daily at dawn.

Camelot.  On your turn, as an Action, you can expend charges you have, or up to as many as you desire, Ethereal Swords, that orbit you (Up to 15), each sword responding to a name and have their own abilities. These swords have a range of 30ft. As a bonus action or reaction, you can call the name of one floating sword to attack the enemy, the sword returns to Arthur after a successful hit and is considered a 'Consumed Charge'. If the sword does not hit, its effect does not activate and does not return. At the end of combat, any remaining floating swords return to Arthur and their charges are restored. The appearance of the Swords are listed by the Knights of the Round. (For example, If you Summon 10 Swords, only 5 Charges will remain inside Arthur). Also when re-summoning an expended sword, it will go down the list of Knights of the Round to the closest name that can be summoned, no single sword can appear on the field twice.

They use the wielder's attack modifiers and have the stats of a +2 Longsword. These Ethereal Swords are immune to all damage and conditions and deal radiant damage, if the target is resistant or immune to radiant, it deals magical slashing instead. These swords are counted as Melee Spell attacks. The swords also return to Arthur when commanded as a bonus action or when the Wielder is unconscious. These abilities require the wielder's Bonus actions and Reactions.

Name	Effect
Lancelot: Right Hand of the King	As a bonus action, Lancelot strikes the opponent twice and on a hit, returns to Arthur. Lancelot scores a critical on a 17-20.
Gawain: King's Bravery	As a bonus action, Gawain strikes the enemy and on a hit, marks them and returns to Arthur. Until the end of your turn, you have advantage on the marked enemy.
Galahad: The Holy Grail	As a bonus action, Galahad Strikes the enemy and on a hit, returns to Arthur. On hit, the wielder restore half the damage dealt by Galahad.
Geraint: Trials of Enid	As a reaction, if you fail a Saving Throw or Check, you can all upon Geraint to strike the enemy and on a hit, return to Arthur, after which you can reroll the die. You must use the new result.
Gareth: Chivalrous Fortitude	As a bonus action, Gareth strikes the opponent and on a hit, returns to Arthur. Upon returning to Arthur, you gain resistance to all damage until the start of your next turn.
Gaheris: Blind Zeal	As a reaction, Gaheris strikes the enemy, and returns to Arthur. Additionally, you can redirect an attack directed at you, to another creature 60ft within your sight. It matters not if the attack can reach or not.
Bedivere: Isle of Avalon	When you would drop to 0 hit points and not killed outright, you may use your reaction to command Bedivere to strike the enemy at advantage, return to Arthur, restore your hit points equal to the damage dealt and teleport you 30ft away from your current location.
Ector: Counsel to the King	When you are hit by an attack, as a reaction, Ector appears and protects you. Ector strikes the opponent and on a hit, returns to Arthur. Until the start of your next turn, you have a bonus to AC equal to your proficiency, including against the triggering attack.
Kay: Nine Nights and Nine Days	As a bonus action, Kay strikes and marks the opponent and on a hit and returns to Arthur. Until the end of the your next turn next, the marked opponent is unable to restore Hit Points.
Dagonet: Dagonet's Mischief	As a bonus action you can Command Dagonet to attack. Roll a 1d4, on a 1 or a 2, Dagonet strikes the opponent, hits unerringly and returns to Arthur, on a  3 or a 4, Dagonet strikes the opponent unerringly then plants itself into the ground. To remove Dagonet, it requires a DC 30 Athletics Check. Additionally, if Dagonet is still planted at the start of the wielder's next turn, the wielder is forced to call back Dagonet as a Bonus Action.
Lamorak: Lamorak's Lament	As a bonus action, Lamorak strikes the opponent, marks them and on a hit and returns to Arthur. The marked opponent has disadvantage on their next saving throw.
Tristan: Ill-Fated Company	As a bonus action, Tristan strikes the opponent and on a hit returns to Arthur, if this attack has advantage, it deals 3d8 extra radiant damage.
Percival: The Grail Knight	As a bonus action or reaction, Percival imitates any expended blade, with respect to how they are used.
Agravain: Agravain's Abidance	As a bonus action, Agravain strikes the opponent and on a hit, returns to Arthur. Upon return, the opponent has disadvantage on all targets except you until the end of its next turn.
Bors: Unbreakable Vow	As a bonus action, Bors strikes the enemy and on a hit, returns to Arthur. On hit, The enemy gains vulnerability to radiant damage from the wielder's next attack of Arthur, unless they have resistance or immunity to such damage until the end of your turn.

 

Sentience

Arthur is a sentient weapon of Lawful Good alignment, with an Intelligence of 16, a Wisdom of 16, and a Charisma of 18. It has hearing and Darkvison out to a range of 120 feet.
The weapon communicates telepathically with its wielder and can speak, read, and understand Celestial and Draconic. 

Personality

Those attuned to Arthur, regardless of their alignment, will become Lawful Good over the course of 5 days as they begin to think like Arthur and become more attuned to him and his personality.
Arthur seeks nothing but the good for the people and the wielder. It constantly strives to make the wielder the epitome of Good.
The Knights, Despite swearing to Arthur, often have squabbles with him and amongst themselves, usually about a woman named Guinevere.

Proficiency with a Greatsword allows you to add your proficiency bonus to the attack roll for any attack you make with it.

Notes: Bonus: Magic, Replace Damage Type: Radiant, wielder chosen by Arthur., Heavy, Two-Handed, Graze