Dusk Dagger

Weapon (dagger), rarity varies

This delicately curved dagger is ornamented with several crescent moon designs. When you hit a creature who is completely in dim light or darkness with this magic weapon, that creature takes an extra 1d4 (uncommon), 1d8 (rare), or 1d12 (very rare) psychic damage.

"There is nothing in the dark that can hurt you."
—Thieves' Cant for nighttime ambush