Ninja of the Mind

In the halls of Bast, hidden in the northernmost regions of the Gaping Maw, lies a temple dedicated to the Mistress of the Shadows. These halls are the location of the legendary clan of Pirate Ninjas, a somewhat silly-sounding group of marauders who specialize in stealth and the world's various elements. In the land of Einess,  they are known as the reapers of the high seas, slaughtering entire ships with nothing but 3 honed clansmen and a small, camouflaged rowboat. Victorious assassinations usually mean that the ship you worked so hard on getting will be sold or dismantled for parts.
Of the various ninjas, the Ninja of the Mind is the ninja who specializes in Illusions and tricks of the mind. They are capable of delivering spectral blows with their weapons and can craft illusions. At later levels, the ability they have to fight with their telepathic abilities, giving them the upper hand in combat. Once they have mastered their respective elements, the Ninja of the Mind fully controls their own techniques, allowing them to become the very element they control.

Illusory Blade

Starting at 3rd level, your mental training and discipline take the form of an illusory blade that hides directly behind your weapon. To you, it appears to be a light glowing pink replica, but it isn't visible to anyone else, except for beings with True Sight or the See Invisibility spell active. Despite appearing to glow, you cannot use it as a source of light.

If you are holding a Dagger, you can summon this illusory blade by using your bonus action. If you make an attack while it is active, you gain 1 additional damage die equal to your weapon damage die. The dagger lasts for 5 minuets, and disappears after. You can do this an equal amount of times to your Int modifier + Proficency.

Bend the Mind

Starting at 3rd level when you pick this archetype, you can distort the vision of the attacking creature, making their aim worse. Using your reaction, if a creature hits you with a weapon attack, you can reduce the damage done by 1d6. If you reduce this damage to 0, you regain 1 use of this feature. Creatures with an intelligence of 4 and below are immune to this feature. You can do this an equal number of times to your proficiency modifier, and regain your uses on a long rest. 

Fractured Consciousness

Starting at 9th level, your skills with mental manipulation grows. You can temporarily salvage a being with a broken or lost mind, and control it. As a reaction, if a creature within 20 feet of you has been injured to the point where it has less than 5 hit points or dies, you can force a small amount of yourself into their mind. The target must make a Wisdom saving throw against your Spell Save DC (8+int modifier+Prof). If failed, You gain temporary control over the creature. You can use your action to make to perform either action, reaction, or movement. It is immediately released after it performs the action.

Vision of the Goddess

Starting at level 13, your skills in mental manipulation greatly improve. You are able to distort one's perception by looking them in the eye, making you seem invisible. You gain an advantage on sleight of hand and stealth rolls if a creature is making direct eye contact with you. 

Way of the Mind

When you reach 17th level, your control over the mind has reached its pinnacle. As an action, instead of striking a target with your blade, you can instead choose to directly attack your opponent's mind through mental projection, causing the target to see you stabbing it, and feel the effect. Only the target and creatures with true sight are able to see this attack. Target creature must be within 60 feet, and be in your vision. This attack deals sneak attack damage, but not your weapon or bonus damage from your illusory blade. Creatures that are attacked in this manner cannot be targeted by this action more than once per day. If the target is killed with this ability, it will appear to morticians and doctors that they had passed away from a stroke. You can do this an equal amount of times to your proficiency modifier, and it resets at dawn.

In addition, when you activate Fractures Consciousness through your sneak attack, you gain the ability to sneak attack through that target. The first target you sneak attack must make a Wisdom Saving Throw against your Spell Save DC. If failed, you take mental control of them for 1 round of combat, taking place immediately after you take control of them. You can make them move to and attack any creature with a weapon they own and are holding of your choosing. If the attack is successful, the 2nd target takes Weapon damage + your sneak attack damage. This affect can only be done once per long rest.