"Bushidō, then, is the code of moral principles which the samurai were required or instructed to observe ... More frequently it is a code unuttered and unwritten ... It was an organic growth of decades and centuries of military career. In order to become a samurai this code has to be mastered."

-- Nitobe, Inazō (1899). Bushidō: The soul of Japan.

Bushido "The Way of the Warrior"

This beautifully forged Katana is crafted from an unknown metallic ore, and sports a blade far larger than regular katanas. The remarkable ore has been rumored to be extracted from the heart of a fallen star. The inscription along the blade's surface are a mixture of sigils, some known and some far older than many written languages.
Upon grasping this weapon's hilt, it begins to hum and vibrate softly. The presence of its many past wielders flicker across the surface of the holder's mind and decide if he or she is worthy of wielding this magnificent blade (DM and player decide if a test is necessary). If you attempt to wield this weapon without proper attunement, the sword begins to vibrate strongly and becomes increasingly unbalanced, denying its wielder and giving disadvantage on any attacks attempted with it.
An attuned wielder is granted the following benefits:

• You gain a +2 bonus to attack and damage rolls made with this weapon.
• While holding this weapon the wielder receives guidance from its past Bushido's past wielders, granting advantage on opportunity attacks.
• The soft humming of the blade keeps the blade spotless, shedding any dirt, blood or other impurities and changing the damage dealt from slashing to force damage. 
• The sword's blade emits bright, bluish light in a 10-foot radius and dim light for an additional 5 feet. The light is similar to starlight.
• While the light persists, you can use an action to expand or reduce its radius of bright and dim light by 5 feet each, to a maximum of 30/35 feet or a minimum of 0 feet.
• Bushido has 7 charges and it replenishes 1d6+1 charges every day at dawn.

The Seven Virtues of Bushidō.

Righteousness (gi)
Be acutely honest throughout your dealings with all people. Believe in justice, not from other people, but from yourself. To the true warrior, all points of view are deeply considered regarding honesty, justice and integrity. Warriors make a full commitment to their decisions.

• You have the ability to cast True Strike at will while holding Bushido.

Heroic Courage (yū)
Hiding like a turtle in a shell is not living at all. A true warrior must have heroic courage. It is absolutely risky. It is living life completely, fully and wonderfully. Heroic courage is not blind. It is intelligent and strong.

• You have the ability to cast Heroism at the cost of one charge. (Charisma or Wisdom modifier)

Benevolence, Compassion (jin)
Through intense training and hard work the true warrior becomes quick and strong. They are not as most people. They develop a power that must be used for good. They have compassion. They help their fellow men at every opportunity. If an opportunity does not arise, they go out of their way to find one.

• You have the ability to cast Healing Word at the cost of one charge. (Charisma or Wisdom modifier)

Respect (rei)
True warriors have no reason to be cruel. They do not need to prove their strength. Warriors are not only respected for their strength in battle, but also by their dealings with others. The true strength of a warrior becomes apparent during difficult times.

• You have the ability to cast Comprehend Languages at will.

Honesty (makoto)
When warriors say that they will perform an action, it is as good as done. Nothing will stop them from completing what they say they will do. They do not have to 'give their word'. They do not have to 'promise'. Speaking and doing are the same action.

• You have the ability to cast Zone of Truth at the cost of one charge. (DC= 8 +Proficiency modifier +Charisma or Wisdom modifier)

Honour (meiyo)
Warriors have only one judge of honor and character, and this is themselves. Decisions they make and how these decisions are carried out are a reflection of whom they truly are. You cannot hide from yourself.

• You have the ability to cast Shield of Faith at the cost of one charge.

Duty and Loyalty (chūgi)
Warriors are responsible for everything that they have done and everything that they have said, and all of the consequences that follow. They are immensely loyal to all of those in their care. To everyone that they are responsible for, they remain fiercely true.

• You have the ability to cast Aid at the cost of one charge. (Charisma or Wisdom modifier) 

source: wiki / Bushido

Proficiency with a greatsword allows you to add your proficiency bonus to the attack roll for any attack you make with it.

Notes: Weapon Property: Finesse, Bonus: Magic, Replace Damage Type: Force, a warrior of lawful alignment with a Charisma or Wisdom score of 12 or higher., Damage, Combat, Heavy, Two-Handed