The kind of device this author is using is Dramatic Irony, when the reader knows something the character does not.
The answer is: He will meet his death in the castle, which he considers a pleasant place
Answer:
Metaphor.
Explanation:
Although the light is not actually chains, it compares the two things to help the reader visualize the lights.
A metaphor for courage might be describing someone as having "the heart of a lion". He does not actually have the heart of a lion, it's a metaphor to show that he is courageous.