Path of the Kensei

When you choose this tradition, at 3rd level, you gain proficiency in all martial melee weapons that lack the two-handed or special property, and those weapons count as monk weapons for you.

Also, you gain proficiency in calligrapher's supplies.

Agile Parry

Also, at 3rd level, you can interpose your weapon between yourself and your foes. When you take the Attack action on your turn with a monk weapon, you gain a +2 bonus to AC until the start of your next turn while you are not incapacitated and the monk weapon is in your hand.

Swordsage Strikes

Starting at 6th level, when you use your bonus action to make an unarmed strike from your Martial Arts feature, you can make an attack with a monk weapon, instead. Also, your weapon attacks with monk weapons count as magical for the purpose of overcoming resistance and immunity to nonmagical attacks and damage.

At 11th level, you can do this with your Flurry of Blows feature as well, replacing one or both unarmed strikes with attacks with a monk weapon.

Master's Riposte

Beginning at 11th level, as a reaction to a creature within 5 feet of you missing you with an attack, you can spend 1 ki point to make a melee weapon attack on that creature.

Executing Blow

By 17th level, when you hit a creature with a melee weapon attack on your turn, you can spend 3 ki points to hit it in an extremely vital area.

At any time before the end of your current turn, you can force the creature to make a Constitution saving throw (no action required). On a failed saving throw, the creature takes 8d10 damage of the same type as your weapon, taking half the damage on a success. A creature that fails the saving throw and has 50 hit points or less is immediately reduced to 0 hit points, instead.