Weapon detectors were security systems aboard Deep Space 9.
In 2369, Miles O'Brien was able to stun a Hunter who walked through a weapon detector on the Promenade. (DS9 episode: "Captive Pursuit")
Later in that year, Neela disabled the weapon detectors on the Promenade, to allow her to bring a phaser later to attempt to assassinate Bareil Antos. (DS9 episode: "In the Hands of the Prophets")