Symbolism is a creative way of using a substance to present a certain idea or characters by giving them symbolic essence that is far from their literal context. One example of this is the use of Sunflower in William Blake’s “Ah Sunflower” where it represents the people.
It may be a Hyperbole or Satire. Since sawing someone's leg off is likely to be exaggerated, it may be a Hyperbole. At the same time, depending on the context of this sentence, it may be said for the purpose of humour, so Satire.