Iron daggers are dangerous weapons in the hands of someone skilled. Light, quick, and sharp as can be, they cleave flesh from bone before the victim knows they’ve been assaulted. This is why they became a favourite weapon of the Children of Shadows.
Though the cult rarely harmed anyone -- it was mostly a social club -- there were those among their number who took their calling seriously.
They smith daggers themselves, and as the blade cooled, they added a single drop of their own blood in honour of their master. Some carved demonic pacts into the blades, though none are known to actually create such a contract.