Cursed Knight

Whether it's by falling in battle to a warlock, losing a lock of hair to a hag coven that curses you, or by signing a deal with a devil and breaking it, there are many ways in which a knight of honor can fall to the forces of evil (or mayhaps the knight was the evil one and was cursed by a deity of vengeance).  However it was done the magnitude of the curse has went beyond the normal standards and has turned you into a Cursed Knight, a curse that cannot be removed unless by the strongest of magics, a curse that usually breaks the targets mind whilst making their bodies stronger so as to turn the knight into an unwilling pawn.  Though through sheer willpower, luck, insanity, finding a greatly valued memento, or the death/abandonment of the master, the creature's mind can find some semblance of what they once were giving the knight a chance to escape the servitude of their new masters, giving them the powers of their cursed form but also the mental weakness that still gnaws at their mind.  With their newfound power a Cursed Knight can use their unearthly powers to create spectral chains, force others to bend the knee, and even make their enemies feel the pain that they would.

Knight's Curse

Beginning when you choose this archetype at 3rd level, choose one of the three curses that the knight suffers from, the curse should best reflect how exactly the person was to suffer, for example a knight beloved by all will be afflicted by the Curse of Charisma so as to be hated by all they would come across.  Though the curses target a certain stat you should speak with your DM to see how that may manifest, for example the Curse of Wisdom may make the character a blind follower who remains oblivious to their surroundings, or mayhaps the exact opposite with the character being distrusting of others and assuming that people are out to get them.  The curse's effect may be only internal or they could also manifest into physical deformations such as a person suffering from the Curse of Charisma looking malformed and disgusting.

Curse of Charisma

You have disadvantage on all charisma based skill checks and saving throws, however once per turn when you hit a creature with a melee attack you can force the creature to make a Charisma Saving Throw (DC 8 + Str + Proficiency) on a fail their speed is reduced to 0 and they have disadvantage on all of their attack rolls until the end of the turn.

Curse of Intelligence

You have disadvantage on all intelligence based skill checks and saving throws, and you cannot read or write in any language (spells such as comprehend languages may suppress the reading disability temporarily but cannot aid with writing, the character cannot learn how to read or write through any non magical means either) however at the start of your turn you gain 1d4 temporary hit points unless you have any other temporary hit points already or are at 0 hp.  

The 1d4 of temporary hit points increases to 2d4 at level 9, and 3d4 at level 15

Curse of Wisdom

You have disadvantage on all wisdom based skill checks, and disadvantage on saving throws against being frightened and charmed, however your AC increases by 4 against any creature you hit on your turn until the start of your next turn.

Chains of the Relentless

You may use your action to target one creature you can see within 60 ft of you that is not two or more sizes larger than you, that target must make a Strength Saving Throw (DC 8 + your Strength bonus + your proficiency bonus), any creature that fails cannot move more than 30 ft away from you (If they're currently beyond 30 ft they are pulled in a straight line until they reach the 30 ft mark), teleportation and other forms of escape magic do not work unless the target succeeds on a Cha Save against the effects saving throw, a character can use their action to make another Strength save against the spell, this effect lasts for 10 minutes, you can use this ability an amount of times equal to your Constitution Modifier, you regain all charges at the end of a long rest.

Spreading Corruption

As a reaction when you are hit by an attack you may force a creature within 60 ft of you (other than the character that hit you) to make a Charisma Saving Throw (8 + Con + Proficiency), on a fail the target takes the damage you would've taken but as force damage, a creature automatically fails this save if they are under the effect of your Chains of the Relentless.  You must take a long rest before using this feature again.

Bend the Knee

As a bonus action target one creature you can see within 60 ft, the target must make a Constitution Saving Throw (8 + Str + Proficiency) on a fail taking 3d10 Force damage and going prone.

Path of Destruction

You become enraged as you slaughter anyone and anything in your path, as an action until the end of the turn you attack every creature within your reach for every 10 ft you move, and all damage dealt this way becomes force damage. You cannot use this ability again until you finish a short rest.

Your base movement speed is also increased by 10 ft.