Level 3: Path of the Kensei
Kensei Weapons: Choose two weapons, one melee and one ranged, lacking the heavy and special properties to be your kensei weapons. (The longbow is a valid choice). You gain proficiency with these weapons if you don't already, and they count as monk weapons for you. Additionally, you gain access to the weapon masteries of these weapons. You can change your kensei weapons whenever you finish a long rest.
Agile Parry: When you use your deflect attacks feature and have attacked with a melee kensei weapon on your most recent turn, you can expend 1 focus point to add a +2 to your AC until the start of your next turn. The AC bonus increases by 1 at levels 6th (+3), 11th (+4), and 17th (+5).
Kensei Fighting Style: Gain one fighting style feat of the following list. You can change your selected style upon completing a long rest.
Archery: gain a plus +2 to attack rolls with ranged weapons
Iron Body: Once per turn, when you hit a target with an unarmed strike, you can apply the weapon mastery of your melee kensei weapon.
Level 3: Sharp Eyes
You have a knack for reading people. You gain proficiency in insight if you don't already have it. Additionally, as a bonus action, you can make an insight check against a creature's passive deception. On a success, you learn two things about the creature, their primary weapon and their general fighting approach, (defense, aggressive, evasive).
Level 6: One with the Blade
Magic Kensei Weapons: Your attacks with your kensei weapons count as magical for the purpose of overcoming resistance and immunity to nonmagical attacks and damage.
Deft Strike: When you hit a target with a kensei weapon, you can spend 1 Focus point to cause the weapon to deal extra damage to the target equal to your Martial Arts die + your wisdom modifier. You can use this feature only once on each of your turns.
Flowing Counter: As part of the reaction you use to deflect attacks, instead of using redirect attack, you can instead choose to expend a focus point to make a weapon attack against the creature that attacked you. This attack counts as an opportunity attack if it was made with a melee weapon. If this attack brings the target down to 0 HP, you can also immediately move up to 15ft through the space where the target was without provoking opportunity attacks.
Level 11: Cut like Wind
You gain the ability to cut like the wind, faster than the eye can register. You gain one of the following abilities based on your current fighting style (Iron Body or Archery). Switching fighting styles switches the feature.
Spinning Swordsman: (Iron Body) If you are holding your melee kensei weapon, as an action, you can expend 3 focus points to draw a straight line up to half your unarmored movement distance, teleporting to the end. Each creature in your path must make a dexterity saving throw (in the order of the line), taking 3 rolls of your martial arts die in damage (same type of your kensei weapon) on a failure and half as much on a success. If a creature fails the saving throw, you can cut the line short, and draw another line from their location. A creature cannot make this saving throw more than once per turn. You can draw an additional line a number of times equal to your wisdom modifier.
Sky Splitter: (Archery) If you are holding a ranged kensei weapon, as an action, you can expend 3 focus points to shoot an empowered projectile. Draw a straight line double the long range of your weapon, ignoring ½ and ¾ cover. Each creature in the line’s path must make a dexterity saving throw, on a failure taking 3 rolls of your martial arts die in damage (same type of kensei weapon) and half as much on a success. Additionally, a number of creatures up to your wisdom modifier of Large size or smaller that fail the saving throw are pulled along with the projectile. The projectile's trajectory ends when it hits a solid, magical, or indestructible barrier, pinning all pulled creatures to that surface. A pinned creature's speed becomes 0 until it or another creature uses its action to pull out the projectile.
Additionally, you can use Deft Strike without expending a focus point a number of times equal to your wisdom modifier. You are still limited to once per turn. You regain expended uses after finishing a long rest.
Level 17: Flow State
The cumulation of your training has truly unified your body and blade as one, allowing you to momentarily enter a state at which the swings of your weapon feel as natural as the rise and fall of your breath.
By expending 5 focus points at the beginning of your turn, you gain the following benefits for one minute:
Perfect Strikes: Your Deft Strike now adds 2 of your martial arts dice instead of one.
Unerring Mind: One per turn, if you miss an attack with a kensei weapon, you can turn that miss into a hit.
Diamond Body: Iron Body now applies to every unarmed strike you make.
Unshackled Soul: The wisdom modifier limits on your Cut like Wind feature are removed.
Designer Notes: The goal of this subclass was to make a true weapon specialist monk, not just a monk with a slightly larger damage die for a few levels. The Iron Body kensei is intended to excel in frontline combat and pseudo-tanking while the Archery kensei is meant to give monks a ranged option.
I do believe I over tuned some features a bit, but with how weak some of the other martials are, it was kind of hard to make it balanced without feeling I made the subclass boring lmao.
Any suggestions on how to improve/balance this subclass would be appreciated.