Fated by Benedict Jacka

 It was difficult for me, at first glance, to determine whether this is a ripoff of the Harry Dresden books by Butcher, or should be considered a tribute to them. So much of the big picture remains the same. Alex Verus is a diviner who runs a small arcana shop in London, and most of the mundane folks around him don't have any idea that magic exists, and would make fun of him for saying it did. There is a world-spanning magicians' Council, with Dark and Light mages. Verus was the apprentice of a Dark mage, but escaped that life, and is not well regarded by the Council; he's just a bit of a renegade, and his little respect for authority. He has an apprentice, Luna, whom he tries to protect by not telling her much about what's really going on.

Starting to sound familiar?

Diviners, as a branch of magicians, have the ability to find out nearly anything, with the right technique and effort. When a Precursor artifact is discovered, both the Dark and Light want to control it, but it has been locked away with some major defensive spells, and when all the other Diviners make themselves scarce, Verus is the default go-to guy for all the factions. He resists getting involved at first, but eventually he is made an offer he can't refuse, and ends up trying to play both ends against the middle, since he realizes that (as the adage goes) anyone who wants the sort of power that the artifact will grant really shouldn't have that much power in the first place.

Of course, as is de rigeur in urban fantasy these days, he has to undergo some intense personal growth and deal with his memories of past traumas before he can move forward.

Looks like there are several more sequels available, so I'll have to throw them on the virtual TBR pile.