Actually, thats a bit strong. Im gonna gut some of the combat stuff, tone down dual weapon kata, and add in a ribbon at mid level. Like how the OHM rolls.
Damage is already spiking with the increased damage dice, so it needs more OOC and less combat oomph.
Path of the Kensei (3rd level):
When you choose this tradition at 3rd level, you learn to extend your knowledge of the martial arts beyond the standard array of monk weapons.
Select one martial or simple weapon without the Heavy quality (other than the lance) to be your Kensai weapon. This weapon is now treated as a Monk weapon for you.
In addition, when you attack with your Kensai weapon, you may replace the weapon damage die with 1d10 unless the weapon also has the reach quality. At 11th level in this class, the increased damage die increases to 2d6. At 17th level in this class it increases to 2d8.
Finally, choose one of the following options:
1) Weapon master: Select one of the Dueling or Great weapon fighting styles. You learn this fighting style. In addition you can expend 1 point of ki to gain advantage on any checks or saves to avoid being disarmed of your weapon, or that targets your weapon.
2) Dual weapon kata: When you are not wearing armor or using a shield, and wield two Monk weapons at the same time, you gain +1 to your AC. When you use your flurry of blows attack, you can choose to make a single attack with one of your monk weapons in place of making two unarmed attacks.
3) Zen archery: You must have selected a bow to use this option. You gain the Archery fighting style. In addition as a bonus action on your turn you can expend 2 points of Ki to take careful aim at a creature you can see that is within range of a ranged weapon you are weilding. Until the end of this turn, your succesful ranged attacks against this target ignore 3/4 and 1/2 cover and deals additional damage equal to 2 + half your Monk level.
One with your Weapon (6th level):
Your attacks with monk weapons are treated as magical.
Stare down (11th level)
As an action on your turn you can expend 1 point of Ki and attempt to stare down or otherwise seek to intimidate your target (pulling your attack at the last second, landing a close shot with a bow, staring your target down, a flourish of your blade etc). Choose a single target that can see you within 60'. That target must pass a [DC 8 + Wis + Prof] Wisdom save or be frightened of you. The target can re-roll the save at the end of each turn to end the condition, becoming immune to this ability for 24 hours on a save.
Deadly Strike (17th level)
When you attack a target and have advantage on the attack roll, and both attack rolls would hit your target, the attack is a critical hit.
That feels a bit more balanced.
