What is the meaning of Barrel full of bears and Percival in respect to the poem Tale of Custard the dragon....???

A Barrel full of bears mean a person without fear or a feeling of anxiety about something that may happen. Here the poet compared Belinda’s braveness with a barrel full of bears.
 In America the meaning of the name Percival is a destroyer. In this poem the dragon is mentioned as the Percival by the poet.