Arclight´s Black Keys

Created by the Archbishop, Archibald Von Arclight. The Black Keys are short one-handed cross hilts with sacred engravings. Primarily used by the inquisition, and wielded in two pairs of three on each hand, on a fan-like formation. When infused with magic they manifest a blade in the form of a slender, rapier-like sword. But they are innately, throwing weapons, used for hunting and assassination. Often used in conjunction with martial arts. 

You gain a +1 bonus to attack rolls and damage rolls made with this magic weapon. When it is paired with another they gain each others bonus up to a +3.

Each deal 1d6 piercing damage when thrown. And 3d4 slashing damage when wielded in a pair of three. When paired they deal 3d6 extra damage of the weapon’s type if the target is a monster, fiend, vampire or spirit. This extra damage applies fully on each blade when thrown for a total of 4d6 piecing damage. They cannot harm pure humans or animals.
(Pure human refers to those who know no sin or have been properly cleansed; If your campaign does not consider vampires a separate race undead can be applied instead)

Letal. When landing a critical hit their damage is doubled.

Spiritual Conduit. Being made from a divine mineral, the Black Keys can be infused with magic of up to 3rd level. 

Magical Infusion. When infused with a spell slot the blades for one pair manifest. One of them individually may be further imbued with an effect of the spent slot’s level that you have prepared.  When thrown, and landing a hit on a creature, the spell takes its pertinent effect. If the spell requires you to make an attack roll it is replaced with the weapon’s.

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

Notes: Needs a Dexterity of at least 18 to wield effectively, Finesse, Light, Thrown, Nick