Black and White Daggers 2014
Weapon, rare, (requires attunement)
These matched daggers are identical except for the stones set in their pommels. One pommel is chalcedony (opaque white), the other is obsidian (opaque black). You gain a +1 bonus to attack and damage rolls with both magic weapons. The bonus increases to +3 when you use the white dagger to attack a monstrosity, and it increases to +3 when you use the black dagger to attack an undead. When you hit a monstrosity or undead with both daggers in the same turn, that creature takes an extra 1d6 piercing damage from the second attack.
Properties
Finesse
When making an attack with a finesse weapon, you use your choice of your Strength or Dexterity modifier for the attack and damage rolls. You must use the same modifier for both rolls.
Light
A light weapon is small and easy to handle, making it ideal for use when fighting with two weapons.
Thrown (range 20/60)
If a weapon has the thrown property, you can throw the weapon to make a ranged attack. If the weapon is a melee weapon, you use the same ability modifier for that attack roll and damage roll that you would use for a melee attack with the weapon. For example, if you throw a handaxe, you use your Strength, but if you throw a dagger, you can use either your Strength or your Dexterity, since the dagger has the finesse property.
Source: Vault of Magic (Kobold Press) · License: OPEN GAME LICENSE Version 1.0a details