Poisons are items that can be used to add a temporary item property. When the weapon hits, the victim may be poisoned.
Poisons can only be applied to piercing or slashing weapons, once applied the poison lasts until a hit is landed, or the charecter who applied it rests (like a magic weapon). The character must succeed at a dexterity check to apply the poison, and any attempt to poison a weapon will use up the poison. Also, attempting to apply poison to a weapon that is already poisoned, a weapon that already has an "on hit" property, or a bludgeoning weapon will fail and the poison will be wasted. (Note: While a morning star does both bludgeoning and piercing damage, it cannot be poisoned.)