Utah Code § 17-60-502: Knives regulated by state.

(1) As used in this section, "knife" means a cutting instrument that includes a sharpened or pointed blade.

(2) The authority to regulate a knife is reserved to the state except where the Legislature specifically delegates responsibility to a county.

(3)

(a) Unless specifically authorized by the Legislature or, subject to Subsection (3)(b), a county ordinance with a criminal penalty, a county may not enact or enforce an ordinance or a regulation pertaining to a knife.

(b) A county may not enact an ordinance with a criminal penalty pertaining to a knife that is:

(i) more restrictive than a state criminal penalty pertaining to a knife; or

(ii) has a greater criminal penalty than a state penalty pertaining to a knife.