Knight of Ghosts and Shadows is an Urban Fantasy novel by Mercedes Lackey. It features a human bard in a three bond with another human and an elf, as well as alot of elves and they're all in California.
I actually collected the Urban Fantasy books by Mercedes Lackey at one point. I didn't get very many of them, though. I thought there were only two books with the bard and three or so of the SERRAted Edge.