Pretty sure this is Cold Burn of Magic (2015) by Jennifer Estep. It's the first book in the Black Blade trilogy.
There Be Monsters Here. . .
It's not as great as you'd think, living in a tourist town that's known as "the most magical place in America." Same boring high school, just twice as many monsters under the bridges and rival Families killing each other for power.
I try to keep out of it. I've got my mom's bloodiron sword and my slightly illegal home in the basement of the municipal library. And a couple of Talents I try to keep quiet, including very light fingers and a way with a lock pick.
But then some nasty characters bring their Family feud into my friend's pawn shop, and I have to make a call--get involved, or watch a cute guy die because I didn't. I guess I made the wrong choice, because now I'm stuck putting everything on the line for Devon Sinclair. My mom was murdered because of the Families, and it looks like I'm going to end up just like her. . .
From a user review:
In Jennifer Estep’s Cold Burn of Magic, a 2015 young adult fantasy novel and the first book in her BLACK BLADE urban fantasy series, the world is divided into mortals and magicks, humans who have some type of magical power. The southern U.S. town of Cloudburst Falls, a hotbed of magical power, caters to tourists who want to see magical people and creatures. It’s reminiscent of Harry Potter World, except that it contains real magic, including pixies who are household servants and monsters like the aptly named lochnesses, who lurk under bridges and require a toll of jewelry or money from all who pass over their bridges. Cloudburst Falls is controlled by mafia-like families with powerful magical abilities, particularly the Draconi and Sinclair Families.
Lila, a seventeen year old orphan, exists on the edges of society as a thief and pickpocket, secretly living in a hidden lair in the local public library. Lila is reasonably content with her life on the fringes, hiding her powerful martial skills and magical abilities from everyone
From another user review:
There are no fire arms allowed in Cloudburst Falls (because they wouldn't work against the magicks anyway) so everybody walks around with swords, daggers and ninja stars beneath their clothes.