Titles not only need to grab reader attention, they need to give a clue as to the tone and genre of the book. For example, I'm working on a collection of short dark fiction that I plan to call Malice and Mayhem: Tales of the Macabre. This should give a pretty good indication of the subject matter.
Which brings me to my latest WIP, formerly known as The Zaphkiel Project. For two years, I've debated what to call this angel UF. Zaphkiel and A Discordant Melody were two titles I played with, but neither were very exciting. And A Discordant Melody sounded more like sci-fi. (Although who's to say I won't write such a story?) For those curious, it relates to the disruption of the planetary harmonics in the story, something I researched for this WIP.
I'm getting ready to submit The Zaphkiel Project, so I needed a title. I brainstormed, writing down character names and anything related to the book: Venus Transit, angels, demons, pentacles, ghouls, Tarot...
And then I wrote the title of a song by Blutengel: "Oxidising Angel".
That brought to mind the title "Exterminating Angel". Surely there had to be several books with that title. But this didn't seem to be the case. Instead, "Exterminating Angel" is better known as a movie by Luis Bunuel.
I doubt anyone will confuse my angel paranormal/UF with Bunuel's satire.