Yin & Yang daishō

The concepts of yin and yang have been around since at least the 1300s BCE, when they were found referenced in inscriptions related to Chinese divination of the weather. One of the first mentions of yin-yang for the concept of cosmic harmony comes from a verse in the shih chang a 6th-century BCE collection of poems compiled by Confucius.

Yin, Chinese for “female” or “moon,” represents darkness, passivity, and the earth. Yang (“sun” or “male”) represents light, activity, and the heavens. The balance of yin and yang were seen to influence health and order within an individual, society, and the entire universe.

When attuning this magical weapon if the user succeeds on an even roll the user will acquire the yin blade first, if the user succeeds on the latter the user will acquire the yang blade. The user must acquire both blades to access some locked spells residing within the blades. When you have acquired one of the blades further attunement rolls will have a -1.

Yin blade

When using this blade the darkness shrouding this blade will result in the user attacking in necrotic damage. Using this will do 1d10 necrotic damage, this blade can be thrown up to 25ft and will return to the user but will instead do 1d8 necrotic damage.

This blade has 2 charges which can be refilled every long rest that can be used to perform various activities such as :

1. You may spend 1 charge to create a decoy that can withstand your characters level + your dex modifier.
2. You may spend 1 charge to channel the darkness within you resulting in an additional attack with the blade.
3. You may spend 2 charges to perform an AOE spread of pure terror resulting in targets of your choosing within a 15ft radius taking 2d6+1 necrotic damage and the targets have to succeed on a DC13 wisdom saving throw or be frightened for 1 turn.
4. You may spend 2 charges to gain +2 to damage rolls but gain 1 level of exhaustion until the user performs a short rest.

Yang blade

When using this blade the light within the users heart will result in the user attacking in radiant damage, Using this will do 1d10 radiant damage, this blade can be thrown up to 25ft and will return to the user but will instead do 1d8 radiant damage.

This blade has 2 charges which can be refilled every long rest that can be used to perform various activities such as :

1. You may spend 1 charge to heal an ally for 1d6+2
2. You may spend 1 charge to shroud your blade in holy flames changing the damage type to fire damage for 2 turns.
3. You may spend 1 charge to shroud your light aura around you adding an additional attack to your turn.
4. You may spend 2 charges to heal all allies within a 10ft radius for 1d8+1.
5. You may spend 2 charges to gain advantage on ability rolls but get disadvantage on skill rolls until next long rest.

Yin & Yang dual blades

When using the blades in conjunction with eachother the damage type changes to force damage due to the mastery of the bodies soul and knowledge of the balance of the universe. Using this will do 1d12 force damage and throwing these will be 1d10 force damage. 

Now having knowledge of the universe the user gains advantage on deception checks and perception checks.

The blades charges increase to 5 charges per long rest and more spells are unlocked as a result of the blades being reunited. You are still able to use all previous spells. Blade charges can now be stacked.

1. You may now spend 3 charges to illuminate the impurities and purities of the casters mind resulting in two more attacks being used with a +1 bonus.
2. You may spend 3 charges to cast a barrier around all allies that can withstand 10 damage and has resistance to magic attacks within a 10ft radius.
3. You may expend 3 charges to summon a holy dagger or a evil dagger which will either heal allies every turn for 1d4 or attack all enemies every turn for 1d4 lasts until it is targeted within a 10ft radius
4. You may expend 3 charges to gain resistance to all physical forms of damage for 30 mins.
5. You may expend 3 charges to increase movement speed by 15ft.
6. You may expend 4 charges to perform the blades ultimate move Divine punishment this is an AOE move with a range of 20ft that deals 1d20 damage to all targets chosen and all targets must succeed on a DC12 wisdom roll or lose gain a level of exhaustion.
7. You may expend 5 charges to gain +5 to damage rolls and allies gain +1 to their damage rolls within a 15ft radius for 10 minutes.

LEVELLING

After killing 50 enemies with this weapon the weapon gains a +1 bonus and can be stacked up to 5 times

After killing 100 enemies the weapon gains another charge and can be stacked up to 5 times

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

Notes: Damage: Force, Damage: Radiant, Damage: Necrotic, Frightened, User must succeed on a DC16 roll, If successful the weapons attune to the user. If failed user takes 1d10 slashing damage. Can be attempted once every short rest. , Versatile, Sap