Those who take this sub-class want to preference being able to flawlessly hit each and every enemy they come across. Honing their skills as a swordsman for years, until becoming one of pure skill and fluidity on the battlefield.

You cannot use a shield with this Sub-class, even if you are proficient.

One with the blade

Level 3:

You gain the following proficiencies: Versatile, Two Handed, Reach, Finesse, Light. Simple Weapons, Martial Weapons.

Additionally you may pick two fighting styles.

You gain the Strike first ability which you may use as many times as your DEX bonus. [Recharged every long rest]

Strike First:

If you are not first in initiative you may temporarily put yourself first.(Tell DM/Gm that you are using this ability) You may use this turn as you would a normal turn, however your speed is doubled for the round.[You go back to your normal initiative roll on the next combat round.]  After using this ability Gain the Strike back passive.

Strike back:

Being fast and agile has its benefits, but also can make you careless. Until your next combat turn your AC is -2.

Precise Strikes

Level 7:

Being an expert of the blade that you are, your aim almost always strikes true. When you attack a monster that you are familiar with, you know its most direct weakness perfect for your blade to penetrate. 

Enemies you have [Fought before, read about, seen before, or have been explained its weaknesses by someone], have -3 AC against {YOUR} attacks, and take an additional ((1d6 - 2) * [Amount of times the weak point has been hit, up to a max of 3])damage. 

I.E: {(1d6 - 2) * 3} = Max additional damage output (12)

A thousand cuts

Level 10:

You gain an additional "Extra attack" (This is to be treated as the 'Extra Attack' feature you get at level 5)

[Yes this means when you hit level 20 you will be able to attack 5 times]

All of your weapon attacks apply bleed damage stacks.

Bleed:

Each time you successfully hit an enemy they gain one Bleed stack. The enemy takes 1HP of damage at the start of their turns for each stack of Bleed they have on them.(This effect stacks infinitely UNLESS the enemy uses a healing spell or applies a healing salve to themselves to get rid of the stacks.)[This effect does not apply to undead or constructs(Basically if it bleeds it can gain stacks)]

Ebb and Flow

Level 15:

With the amount of training and combat you have been through you are able to predict where and when enemies may strike.

You cannot be surprised. You gain advantage on Perception checks.

As a reaction if you are within 5ft of an ally who is being attacked, you may block an incoming attack with your sword. You reduce the enemies attack roll. [Roll a d12, half it and round up](Max reduction is 6 - I.E: Enemy rolls a 17 + 6 totaling 23, and you roll a 9. You would reduce their attack roll by 9/2 ^ = 4. Making their attack roll actually a 19)

However doing this put you slightly off-balance. (Gain the Off-balance de-buff) 

Off-balance: 

Until your next turn or when helped by an ally(Help action), enemies have advantage on attacks made against you.

Master of the blade

Level 18:

Your mastery of the blade has become unparalleled to all others.

You gain Expertise with one weapon style of your choice. (I.E: Longsword, Greatsword, Etc.)

You reroll anytime you would get a 1 on an attack.

Your attacks now bleed for an additional stack (2 Stacks per hit).

As a bonus action you may now swap between three sword forms.(Gedan-no-kamae[Defensive Style], Hassō-no-kamae[Aggresive Style], Chūdan-no-kamae[Balanced Style])

Gedan-no-kamae:

While performing this style you gain a +3 to AC and cannot be affected by the Off-balance de-buff. You can only attack up to 2 times while in this form.[It does not matter if you can attack more times due to abilities and feats, you are capped to up to 2 MAX)

Hasso-no-Kamae:

While performing this style you have a -2 to AC, and the Off-balance de-buff makes you go prone instead. However your attacks deal an additional 2d6 slashing damage.

Chudan-no-Kamae:

You gain a +1 to AC, and deal a  flat +2 additional slashing damage to each of your attacks.