Source: Waterdeep - Dragon Heist

Wondrous item, rare (requires attunement)

This armband appears to have thin daggers strapped to it. As an action, you can pull up to two magic daggers from the bracer and immediately hurl them, making a ranged attack with each dagger. A dagger vanishes if you don't hurl it right away, and the daggers disappear right after they hit or miss. The bracer never runs out of daggers.