Could you tell me please, where can I find more information about Epithet?
There is information available on eNotes on the term epithet. Directing you to that information will be much more concise than defining the term here, as it is a term with a number of meanings.
You can follow this link for a lengthy description of the term in its various meanings: http://www.enotes.com/topic/Epithet
Also, for future reference, you can do a search within eNotes to find pages and links to quite a bit of material on many subjects, including specific terms like this one.
When you do a search for epithet, a page/tab shows as a Wikipedia result. Clicking the tab takes you to an eNotes page with all the information you are looking for.