It's also extremely vague. The line put me in mind of clickbait article titles: "An exiled swordsman faces many forms of darkness and secrets that will change his life and the world forever. Find out what those secrets were here!"

Also, I'm a little unclear as to what you mean by "hookline." I associate hooks in writing with a line or section at the very beginning of the story that draws the reader in. Something that makes them want to read. What you seem to be looking for is a one-line summation. If that is the case, then you actually need to say something about the plot. Something like:
"Zaahira Kazemi, a young woman with a college degree struggling to find a job, becomes a henchman for a costumed criminal."
or
"A foppish layabout from a wealthy family stumbles upon a conspiracy involving smuggled dwarven weapons and mage-hunters."
There's got to be some meat on those bones, if you follow me.

PC

The first things that springs to mind is 'that's cliché, how is this book any different than any other fantasy book?' Unfortunately, I can't offer anything positive without knowing anything about the book.