interesting, if the bird is the direct object, shouldn't を be after 鳥 not 刀?
or maybe the 刀 is the direct object and the 鳥 is indirect object marked by に、the verb means to add...?
so i suppose it means literally "adding the sword to the bird" or "stabbing the bird/chicken using the sword"
just a wide guess, is it from a poem by the way?