The family name of Aureolus Paracelsus (1493-1541). He is said to have kept a small devil prisoner in the pommel of his sword.
Bombastus kept a devil's bird Shut in the pommel of his sword, That taught him all the cunning pranks Of past and future mountebanks.
Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894
More on Bombastus from Infoplease: