Keyblade Weilder

With the power of the Keyblade, you can open and seal any door, any gate, any lock. You have the power to spread Light or Darkness wherever you walk, and your unwavering heart allows you to be ever brave in the face of adversity. Even when not wielding a Keyblade (Such as the one I have shared to this site) you can imbue your normal weapons with magical properties.

Weapon of The Heart 

You have either been given some training or learned on the road. In either case, you have learned the mysterious arts of your weapon. When you take this Archetype at 3rd level, you gain a magical Keyblade of Light if you are Good and/or Lawful, or a Keyblade of Darkness if you are Chaotic and/or Evil. (DnDBeyond won't let me link them, so you'll have to dig around my submitted homebrews to find the ones I made, or brew your own with DM permission.)

Keyblade Training

Beginning at 3rd level, your training with the Keyblade has made you a gifted warrior. You gain the following benefits:

Keyblade Arts You learn four Key Arts of your choice from the list below. You learn one additional Key Art at 7th, 10th and 15th level. While you can learn any Key Art that you want, each requires you to fulfill a certain condition to activate (For example, performing a number of  attacks or wielding a weapon in each hand). You perform Key Arts in place of the Attack action on your turn, however you may still take additional actions as if a Key Art were your Attack Action. So long as you have enough Key Dice, you can perform multiple Key Arts per turn, but only one per action.

Key Dice. You have a number of Key Dice, which are d6, equal to your proficiency bonus + your Wisdom modifier. They are expended when you use them. These dice are recovered after a short or long rest.

Saving Throws. Some of your Key Arts require your target to make a Saving Throw to resist the effects. Your Save DC is Calculated as follows:

Key Art Save DC = 8 + your Wisdom modifier + your proficiency bonus

Explosion

Condition: You are able to cast at least one spell or cantrip. All creatures adjacent to you must succeed a Dexterity Saving Throw or take Force damage equal to your Key Die + your Wisdom modifier.

Finishing Leap

Condition: You have successfully made at least three attacks this turn. Your target must make a Constitution save. On a failure, you make a melee attack with your equipped weapon that automatically succeeds. You add your Key Die to your damage roll for this attack.

Guard

Condition: You are not wielding more than one weapon. Your AC increases by the value of your Key Die until the beginning of your next turn, an enemy successfully hits you with an attack, or you take another action, bonus action, or reaction. Attacks made against you by an enemy you are facing and can see have disadvantage.

Magnet Spiral

Condition: You are not currently in a Drive Form. Creatures within ten feet of you must succeed a Dexterity saving throw or be pulled within melee range of you, at which point you make a single melee weapon attack against each creature in melee range. You add your Key Die to the damage you deal with this melee attack (you only roll once).

Slapshot

Condition: You are not currently engaged with a hostile creature. Move up to 15 feet in the direction of a hostile creature you can see. Make a melee attack with  your equipped weapon. If the target is currently engaged with another creature, you make this attack with advantage. You add your Key Die to your damage roll for this attack.

Sonic Blade

Condition: You have at least 18 Dexterity and are not wielding more than one weapon. You can move up to twenty feet in the direction of a creature no more than twenty feet away. Make a melee attack with your equipped weapon against that creature. You may continue moving toward and making attacks against creatures within ten feet of you until you have made seven attacks or failed to hit. Your movement does not provoke attacks of opportunity during this action. You add your Key Die to all attack rolls made during this action.

Strike Raid

Condition: You are not wielding more than one weapon. You make a ranged attack with your equipped weapon. If your equipped weapon is a Magic Weapon, it gains the thrown property with a range of 30/60. A target may make a Dexterity Saving Throw to avoid the attack. On a failed save, you make two attacks with your weapon, one as the weapon is thrown and one as it magically returns to you. You add your Key Die to your damage roll for this attack.

Stun Impact

Condition: You have made four successful attack rolls this turn.. You strike the ground, sending out a wave of force from your Keyblade. All creatures within 10 feet of you must make a Constitution Saving Throw or be knocked prone and take force damage equal to your Key Die.

Vicinity Break

Condition: You are engaged with more than one creature. Make a melee weapon attack against all adjacent creatures. You add your Key Die to this attack roll. Any creature you successfully his with this attack is pushed back 5 feet.

Reaction Command

At 7th level, you have learned to predict and counter enemy attacks. As a reaction to an enemy attack that targets you or an ally within ten feet of you, you may expend 1 Key Die to perform a Key Art that you know, however you do not perform an attack prior to the use of this Key Art if you normally would have to.

Once More

Beginning at 10th level, your Heart has granted you the power to continue despite the most dire of odds. If your Hit Points would be reduced to zero, you can instead drop to 1 Hit Point. You can then take the Attack, Disengage, or Key Art actions, and your Disengage does not provoke an attack of opportunity. Once you use this feature, you cannot use it again until you complete a long rest.

Keyblade Mastery

You have mastered the secrets of the Keyblade the the methods of wielding it. Your Key Dice become d10. You also have advantage on attacks made against Monstrosities, Aberrations, and Undeads.

Drive Form

At 15th level, as you grow to understand the nature of the Heart and the balance between Light and Darkness, your Keyblade amplifies your strength. You get a number of Drive Points equal to your Proficiency Bonus + your Wisdom modifier. You can spend these points to use a Drive Form. Drive Forms are temporary transformations that grant special skills. You must spend 1 Drive Point at the start of your turn to maintain a Drive Form, otherwise you revert to normal.

You can use any Drive Form, as long as you meet the conditions. You can enter each Drive Form once and regain the ability to do so after you complete a long rest.

Final Form

Prerequisite: You have the ability to use Master Form and a maximum of 8 Drive Points. You can spend a Bonus Action and 2 Drive Points to enter this form.  When you enter this form, You can summon any weapon you own into a free hand, if you have one, as a free action, which becomes a Keyblade. This lasts until you exit this form. You gain temporary Hit Points equal to 9 times your Fighter Level.  You are considered to have the Two-Weapon Fighting style while in this form, if you didn't have it before. Both of your equipped weapons are floating, and wielding them does not require a free hand. They can each attack a creature in melee range as a bonus action after casting a spell. While in this form, the number of attacks you have gained from your Extra Attack Fighter feature increases by one, for a maximum of five. Spells or Cantrips you cast which have a casting time of 1 Action can be cast as a Bonus action instead if you have already cast a spell this turn. When this form ends, you suffer 1 level of Exhaustion.

Master Form

Prerequisite: Either your Strength or Intelligence is at least 15 and the other is at least 16. You can spend a Bonus Action and 1 Drive Point to enter this form.  When you enter this form, You can summon any weapon you own into a free hand, if you have one, as a free action, which becomes a Keyblade. This lasts until you exit this form. You gain temporary Hit Points equal to 7 times your Fighter Level.  You are considered to have the Two-Weapon Fighting style while in this form, if you didn't have it before. One of your equipped weapons is floating, and wielding it does not require a free hand. It can attack a creature in melee range as a bonus action after casting a spell, and attacking with it after making an attack with your main weapon is not considered a bonus action.

Valor Form

Prerequisite: You have 16 Strength. You can spend a Bonus Action to enter this form. You become unable to cast spells, if you could before, while in this form. When you enter this form, You can summon any weapon you own into a free hand, if you have one,  as a free action, which becomes a Keyblade. This lasts until you exit this form. You gain temporary Hit Points equal to 9 times your Fighter Level. While in this form, the number of attacks you have gained from your Extra Attack Fighter feature increases by one, for a maximum of five. You are considered to have the Two-Weapon Fighting style while in this form, if you didn't have it before. You have advantage on Dexterity Saving Throws.

Wisdom Form

Prerequisite: You have at least 16 Intelligence. You can spend a Bonus Action to enter this form. You become unable to make melee attacks, and you cannot wield more than one weapon. When you make an attack with your equipped weapon, you instead make a number of ranged spell attacks equal to your proficiency bonus. If you can cast spells, you can also cast Spells or Cantrips as a bonus action if they have a casting time of 1 action or faster, and damage or healing you do with Spells you cast of second level or higher is increased by your Wisdom Modifier. You add your Wisdom modifier to your AC when you are the target of a ranged or magical attack, and you have advantage on saving throws against Spells.