Given the fact that the Sonnet's focus is the description of love, I think that you could find much in it to serve as a figure of speech. In my mind, one of the strongest figures of speech would be the description of love as a star in the heavens. In lines 5 and 6, Shakespeare describes love as a "fixed mark, that looks on tempests and is never shaken." The comparison of love as a star in the heavens to which all aspire and direct their attention connotes the celestial condition of true love and emphasizes its "other worldly" quality. Another example of figurative language would be lines 9 and 10, where Shakespeare describes love as something that is not "Time's fool." The implication here is to use figurative language in describing love as something permanent, not to be withered through the impact of time. In describing it as "time's fool," Shakespeare might be suggesting that love carries with it a sense of lasting. I would argue that the last example of figurative language could be found using the same type of analysis as outlined above. In the opening lines, I would submit that one can find an example of figurative language in how Shakespeare conceptualizes love. In attempting to find examples of figurative language, seek to find ways that Shakespeare describes what love is. In the opening lines lies one such example.
The three examples of striking images which Shakespeare uses in his sonnet 116 are:
1. "It is the star to every wandering bark." Love is constant like the bright North Star with which ancient sailors navigated their ships safely and correctly to their destinations. The star is a metaphor which symbolizes the constancy of love.
2. "wandering bark" Here 'bark' which is literally a part of a tree is a metonymy for ship, because in Shakespeare's time there were only wooden ships.
3."his bending sickle" A sickle is a tool used by the farmer to reap the ripened corn. Here sickle is a synecdoche for 'Father Time.' Father time is usually represented as an old man carrying a scythe or a sickle to reap the ripened corn. As men grow old and 'ripen' with age, Father Time cuts us down with his scythe. True love according to Shakespeare is beyond the reach of Father Time's scythe, that is, it will live forever.