Blood Dagger

This looks like a simple chipped stone dagger upon first inspection. After a kill with it, however, it absorbs any blood on it and is warm to the touch.

Properties: Finesse, Light (Cannot be thrown without taking 2d6 psychic damage)

Without Attunement With Attunement
 * Atk+1, 1d4 piercing damage
 * Atk +4, 1d4 piercing damage + 1d4 additional damage to humans
 * Critical hits trigger an additional 1d4 necrotic damage
 * Once per long rest, a successful attack will do an additional 1d8 necrotic damage to target causing the wounded target to take 1d4 damage at the beginning of every round.
 * If parted from the dagger, the adventurer's max hps decrease by 3 per level until reunited with the dagger. The adventurer knows where the dagger is at all times.