Answer: Personification
Explanation:
On this current sonnet, personification is the figure on speech that's being used.
This literary concept refers to those writings in which the author presents non-human objects, such as animals, furniture or even an abstract idea, and gives them human characteristics in order for the reader to feel as if it was being talked about one (human).
Following Sonnet 10 as an example, we can see that the author is personifying death as if it was speaking to us personally, and asking not to be afraid from it.