What's in a Title?

So my editor wants to talk about titles for the new series. Titles are sometimes easy - Transformation, Song of the Beast, Flesh and Spirit. They can bubble up early out of the story, sometimes before I know what they really mean - The Soul Weaver, Daughter of Ancients.

Some titles are just hard - Son of Avonar. That one took me a while because I had to step back and see that the core of the story, the prime motivator, the piece that changed EVERYthing, was the "son" in question, even though