Provide the excerpt for a proper answer...
He is using the appeal Ethos which is an appeal that persuades the audience.
You know it is not Logos because there are no numbers/statistics in the excerpt and it is not Pathos because that appeal deals with making the audience feel bad and emotional.
The letter was posted by his father.
The only thing i can see is he maybe doubted if he should have made the decision, just read the 3rd stanza then write what u think he’s feeling
With a good word choice,the writer creates a mental picture in your head. For the reader by using words that are specific and accurate. The writer used strong action verbs whenever possible to show the reader what is happening rather than tell the reader. (Hope this helps !! If I’m not right I’m sorry for my mistakes)