609.66 only explicitly makes automatic knives and brass knuckles illegal. Otherwise, it doesn't actually make carrying any kind of knife illegal, unless used to harm someone, or for illegal purposes.
609.66 DANGEROUS WEAPONS.
Subdivision 1.Misdemeanor and gross misdemeanor crimes. (a) Whoever does any of the following is guilty of a crime and may be sentenced as provided in paragraph (b):
1) recklessly handles or uses a gun or other dangerous weapon or explosive so as to endanger the safety of another; or
(2) intentionally points a gun of any kind, capable of injuring or killing a human being and whether loaded or unloaded, at or toward another; or
(3) manufactures or sells for any unlawful purpose any weapon known as a slungshot or sand club; or
(4) manufactures, transfers, or possesses metal knuckles or a switch blade knife opening automatically; or
(5) possesses any other dangerous article or substance for the purpose of being used unlawfully as a weapon against another; or
(6) outside of a municipality and without the parent's or guardian's consent, furnishes a child under 14 years of age, or as a parent or guardian permits the child to handle or use, outside of the parent's or guardian's presence, a firearm or airgun of any kind, or any ammunition or explosive.
Possession of written evidence of prior consent signed by the minor's parent or guardian is a complete defense to a charge under clause (6).
(b) A person convicted under paragraph (a) may be sentenced as follows:
(1) if the act was committed in a public housing zone, as defined in section 152.01, subdivision 19, a school zone, as defined in section 152.01, subdivision 14a, or a park zone, as defined in section 152.01, subdivision 12a, to imprisonment for not more than one year or to payment of a fine of not more than $3,000, or both; or
(2) otherwise, including where the act was committed on residential premises within a zone described in clause (1) if the offender was at the time an owner, tenant, or invitee for a lawful purpose with respect to those residential premises, to imprisonment for not more than 90 days or to payment of a fine of not more than $1,000, or both.
Also,
illbits wrote: As a side note, the statute restricting carry of knives in the city of Minneapolis has an exemption for carry permit holders acting "within the scope of their permit." Other cities may have similar language in their statutes.
Not just knives, but weapons defined as:
Weapon means any device designed as a weapon and capable of producing death, great bodily harm, or substantial bodily harm; or any other device or instrumentality which, in the manner it is used or intended to be used, is calculated or likely to produce death, great bodily harm, or substantial bodily harm, or the reasonable and immediate fear thereof. "Weapon" includes Chinese stars. "Weapon" does not include (1) except when used as a weapon, a folding knife with a blade of four (4) inches or less in length, measured in a straight line from the point to the handle; or (2) a firearm, unless expressly included by section 393.20(b).]
Better get out those backup throwing stars!