A writer who chooses, for the title of his novel, an obscure word which will send most people rummaging for a dictionary, might be someone with lurking feelings of inferiority, who feels he has to establish a position of superiority vis-a-vis his readers. In that case, he might also do this by (inter alia) using common phrases in uncommon (and not necessarily meaningful) ways, to keep his readers guessing, which he’s certainly succeeded in doing in this case. Of course, the phrase may not be in the original book --- but my guess would be, it is.
The book and the more popular film The revenant is a story about revenge. The main character in the film, and the book, is viciously mauled by a Grizzly bear and is abandoned by two men who were ordered to take care of him before he dies. He manages to survive and his most passionate desire is revenge.
There is more to the story, but the gist is about the revenant: one that returns after death. Therefore, the writer chose, in my opinion, the more appropriate word. If there is not a better word then one must choose the obscure or more challenging word.
Revenant might be an obscure word, but it is the more appropriate and precise word for the title.