So what makes a unique name for a location in an epic fantasy novel? How can it be original?
I usually like to divide location names into two categories: 'Fantasticals' and 'Naturals.’
Fantasticals are names that are obviously suited for fantasy. They're the names that pop up that seem to have been randomly pulled out of one's head. Narnia was named Narnia simply because the combination of letters--Narnia--seemed to fit. Fantastical names are those words that you just randomly make up. "Sharlae Forest,” "the Ocean of Ramair"--such names I just pulled out of my head.
Now, 'Natural' names, as you might have already guessed, are names that mean something. Now, within the Natural section, there are two different subtypes. In the Bible, every name--place or otherwise--meant something in the language in which it was named; this is the first type of name. The second type is an actual combination of words to name a place. In The Hobbit, there is a town simply called 'Laketown.'
Fantasy authors can use either one of these, or, in order to make things truly original, can choose to combine both kinds of these names.
Tolkien used this technique masterfully in The Lord of the Rings--many place names meant something, but only in other languages like Quenya and Sindarin (different Elvish languages.) He also named places using the other kind of natural names: 'The Shire,’ 'Hobbiton,’ 'Rivendell,’ and 'The Old Forest,’ to name a few.
But if an epic fantasy book can combine both kinds--and give the novel an echo of old world we, the readers, have left behind--and an eerie feeling of newness, then that novel has succeeded.
To truly have unique names for locations in fantasy, a writer should probably use all of the kinds of names to make richly imagined, unique names for all of the places in the novel.