The way of the Shadow Ninja 

Ninja weapon mastery

Ninja Weapons. Choose two types of weapons to be your Ninja weapons: one melee weapon and one ranged weapon. Each of these weapons can be any simple or martial weapon that lacks the heavy and special properties. The longbow is also a valid choice. You gain proficiency with these weapons if you don’t already have it. Weapons of the chosen types are monk weapons for you. Many of this tradition’s features work only with your Ninja weapons. When you reach 11th level in this class, you can choose another type of weapon — either melee or ranged — to be a Ninja weapon for you, following the criteria above.

Agile Parry. If you make an unarmed strike as part of the Attack action on your turn and are holding one of your ninja weapons, you can use it to defend yourself if it is a melee weapon. You gain a +2 bonus to AC until the start of your next turn, while the weapon is in your hand and you aren’t incapacitated.

Precise Shot. You can use a bonus action on your turn to make your ranged attacks with a Ninja weapon more deadly. When you do so, any target you hit with a ranged attack using a Ninja weapon takes extra damage of the weapon’s type equal to your Martial Arts die. You retain this benefit until the end of the current turn.

Way of Pain. You gain proficiency with a poisoner's kit.

One with the Blade

At 6th level, you extend your ki into your Ninja weapons, granting you the following benefits.

Magic Ninja Weapons. Your attacks with your Ninja weapons count as magical for the purpose of overcoming resistance and immunity to nonmagical attacks and damage.

Harness the power of the blade. One you turn when you use the furry of blows to make two unarmed strikes you may use you Ninja Weapons instead of your regular unarmed strikes for one or both attacks, but the damage will be equal your Martial arts dice of your monk Level with an addition +1, and you gain no other additional damage that the weapon could produce. For example if you're a 5th level monk with a Martial arts dice being 1d6 your damage would be 1d6+1+Dex or Str mod which ever you used for your attack. 

Shadow Step

At 6th level, you gain the ability to step from one shadow into another. When you are in dim light or darkness, as a bonus action you can teleport up to 60 feet to an unoccupied space you can see that is also in dim light or darkness. You then have advantage on the first melee attack you make before the end of the turn.

Ninja weapon

By 11th level, you have learned to become one with one additional Ninja weapon. You can choose another type of weapon — either melee or ranged — to be a Ninja weapon for you, following the criteria from Ninja weapon master. 

Cloak of Shadows

By 11th level, you have learned to become one with the shadows. When you are in an area of dim light or darkness, you can use your action to become invisible. You remain invisible until you make an attack, cast a spell, or are in an area of bright light.

Death Strike

Starting at 17th level, your melee strikes with your Ninja weapons can channel the energy of death into a creature. When you hit with a melee attack using a Ninja weapon you may expend 1 to 10 ki points. The target must make a Constitution saving throw, and it takes 2d10 necrotic damage per ki point spent on a failed save, or half as much damage on a successful one.