I am desperately looking for an epithet about Telemachus in the Odyssey and 2 quotations that prove this epithet.

Go to book 2 page 3.  You will find a reference to Telemachus by Antinous.  He refers to Telemachus as "my fine fire-eater."  The epithet is born out on page 1 by Telemachus berrating the suitors who were taking advantage of his house.  You can also find a quotation on page 1 of book 3.  Look at the paragraph where Telemachus initially speaks to Nestor and the paragraph prior to the speech.  The text states, "Telemachus answered boldly."