Parents of kids in city schools have new cause to worry: Seizures of knives from students soared 92% since Mayor Bill de Blasio’s first year in office.

An analysis of NYPD data by The Post’s Selim Algar found cops confiscated nearly 1,700 knives during the 2018-19 school year. The number of all kinds of weapons, meanwhile, topped 2,700, up 60% since 2014-15.

Algar’s findings echo previous reports of rising numbers of weapons in city schools. The logical explanation: Kids feel more frightened and believe they need a weapon in school for self-defense.

Department of Education spokesman Will Mantell pooh-poohed that idea. Instead, he attributes the spike to unannounced metal detector scanning and kids feeling freer to report on their peers.

That might account for some of the rise, but it surely doesn’t explain why students feel the need to bring the weapons to school in the first place.

Mantell claims “the schools are safe and getting safer,” but if that were true, then at some point wouldn’t you expect the number of weapons found to drop, not climb?

School safety agents union chief Greg Floyd seems more on target: He blames a rise in bullying among students, after Team de Blasio relaxed school discipline policies. Troublemakers no longer fear swift, meaningful punishment for misbehavior.

We’ve long warned that de Blasio’s relaxed discipline could lead to more disorder in the classroom, and reports on “school climate” have reflected that, as does the 92% spike in knives.

Alas, for de Blasio, “restorative justice” (read: mere slaps on the wrist) is all that’s needed; harsher measures — suspensions, for instance — are too rough on kids.

In 2017, the city suffered its first school slaying in 25 years, when a Bronx teen, who felt bullied, stabbed a classmate. Pray it doesn’t take another killing for de Blasio & Co. to see the flaws in their logic.