A matched pair of almost identical, exceptionally light, and perfectly balanced, yet unassuming blades. Forged from ancient steel, these sacred weapons appear almost mundane. The only visible difference between them being Yins's handle is wrapped in black cloth, and Yang's in white.
When either blade is wielded by itself, or they are both wielded together but not attuned to the wielder, they are simple +1 magic weapon.
When both Yin and Yang are held at the same time and attuned to the wielder, the following applies:
- The blades become +2 magic weapons
- The wielder gains +2 to their AC.
- Should either weapon score a critical hit, the next attack from it's twin is made with advantage.
- If the wielder's action grants multiple attacks, either weapon may be used for the subsequent attacks.
- If the wielder is subject to a melee attack that misses the wielder's AC by 1 or 2 points (i.e. it would have hit if it weren't for the effect of Yin and Yang being held at the same time), that attack is blocked by one of the blades, and the wielder gains an attack of opportunity against the aggressor with the other blade.
Proficiency with a Longsword allows you to add your proficiency bonus to the attack roll for any attack you make with it.
This weapon has the following mastery property. To use this property, you must have a feature that lets you use it.
Sap. If you hit a creature with this weapon, that creature has Disadvantage on its next attack roll before the start of your next turn.
Notes: Bonus: Dual Wield Armor Class, Advantage: Melee Attacks, Bonus: Extra Attacks, Bonus: Melee Attacks, Fighter. Although these are two separate weapons that can be wielded individually, they must be attuned to as a pair and only take up one attunementv slot., Damage, Buff, Combat, Versatile, Sap
Version 2 here: https://www.dndbeyond.com/magic-items/3070405-yin-yang
Version 2.1 - minor wording changes.
https://www.dndbeyond.com/magic-items/3082159-yin-yang