You get spellcasting too. I can't be bothered writing out a list of spells though, so you can pick any spells at all. Also, they are not spells, they are called contracts - you only need a Verbal component for them, and you cast them by expending a number of Mana Points equal to the level of the spell contract. You can only cast contracts of level equal to your Max Mana number or lower. You know a number of spells equal to 2 * (your arcane blade mystic knight level + your magic stat). You also get to pick cantrips small contracts.

When you hit with a weapon attack, you can expend a number of Mana Points up to your Mana Max to add 1d10 damage for every 1 point expended. Also, you add your Proficiency bonus to your damage rolls.

You get expertise in two skills of your choice. You get additional two expertises at level 6, 11 and 16.

You are good even with no armor on. Whether you are or aren't wearing armor, you always add twice your magic stat to your armor class.

Choose one of the following stats: Strength, Dexterity, Constitution, Intelligence, Wisdom, Charisma. This is your magic stat. Whenever a class feature refers to your magic stat, use this stat. You also use this stat for your attack rolls with any weapon you hold.

You start with any equipment you want, in addition to the equipment granted by your background.

I can't be bothered writing lore, because the class is rushed out. You can use this class for anything, realy. It has zero identity. Also, zero artworks because why bother.

Free Feat Level. At 2nd level, you gain Charger and Heavy Armor Master feats.

Advantaged Also at 2nd level, you can choose to use your bonus action to get advantage on an attack roll, saving throw or a skill check.

Pact Boon When you reach 3rd level, you gain the same feature as Warlocks do (PHB page 107).

ASI You get an Ability Score Increase at 4th, 6th, 8th, 10th, 12th, 14th, 16th and 19th level. You can also choose feat.

Extra Attack Starting from 5th level, you make two attacks when you use an Attack action on your turn. Starting from 11th level, you can make three attacks as part of Attack action instead.

Fighting Style At 6th level, you get a fighting style from those presented in the Fighter class in PHB.

Extra Action When you reach 9th level, you get an Extra Action. Once per turn, you can get an additional action, bonus action or reaction. Additionally, you can make any action as a bonus action, and any bonus action as an action on your turn.

Ultimate Double Wielder of Swords and Other Weapons When you reach Level 15 of Arcane Mystic Blade Master Knight class, you can wield a two-handed weapon in one hand. You can also wield two weapons like this at the same time. Don't worry guys, I saw it in WoW, I think I know what I'm doing! It worked there, it will work here too! Also, you can finally add your Proficiency Bonus to your AC, attack rolls, skill checks and saving throws. Just an off-hand note, because I didn't want to make up a new feature for it.

Eternal Body Starting from 17th level, you stop aging and don't need to eat or drink or sleep and you can trance all night and you have poison immunity and immunity to poisoned condition, as well as immunity to all magical and nonmagical diseases.

Touch of Death When you reach 20th level, you are very strong. You can use an action to touch a creature and expend 10 Mana Points. The creature must succeed on a Dexterity and Constitution saving throw. If it fails on at least one of them, it dies instanatly.

Immortality At 20th level, you also stop aging (again) and when you die, you are resurrected 3 days later or something with all your equipment. Your corpse with its equipment doesn't disappear, you just reappear somewhere else. A perfect clone.

Forever Leveling Also at 20th level, you can choose to start investing levels into other subclasses. Your proficiency bonus keeps increasing for every three levels of your total character level, and when you get a subclass level, you get all of the subclasses' features.