Final answer:
Grimsby calling the character his "one shining achievement" is a use of metaphor, which is a direct comparison without using "like" or "as". This figure of speech highlights the character's importance to Grimsby in a significant and symbolic way.
Step-by-step explanation:
The literary device used when Grimsby calls the character his "one shining achievement" is a metaphor. A metaphor is a figure of speech that makes a direct comparison between two things that are not alike but have something in common, without using "like" or "as". In this case, Grimsby is not saying that the character is literally a shining light, but is comparing the character's significance to him as being as important and bright as a shining achievement in a metaphorical sense.Hyperbole is an exaggeration that is not meant to be taken literally, simile uses "like" or "as" to make a comparison, and irony involves a contrast between expectations and reality. Since the phrase does not use "like" or "as," it is not a simile, nor is it an exaggeration or a statement of irony, which leaves metaphor as the main answer.In conclusion, Grimsby's expression "one shining achievement" is a metaphor because it compares a character to a bright, notable success without using "like" or "as" and suggesting a deep level of significance and pride associated with that character.