Final answer:
The figurative language device in the bolded text is personification, which attributes human characteristics to the light, suggesting it acts on its own to increase the scene's tension.
Step-by-step explanation:
The figurative language device that appears in the bolded text is personification. Personification is a literary device where human qualities are given to objects, animals, or ideas. In the provided text, the light is personified as it 'leaped from his hold' which implies an action that a living being would do, giving the light human-like capabilities of movement. This creative expression enhances the dramatic tension of the scene by suggesting the light is almost willfully escaping Heathcliff's grip, exemplifying his agitation.