poison darts

Shouldn't I have to be hidden to use these? This is in the battlefields. A Damp Tunnel [Exits: east west] Leaning heavily on his sword, this large guard rests briefly in the night. hide You cannot hide here. pds guard Carefully sizing up your target, you release a tiny poisonous dart with a flick of your wrist. Your poisonous dart nicks the skin of a large guard. A large guard yells 'Ouch!' A large guard clutches the tiny scratch with surprise as his eyelids suddenly droop.