plain answers are hard to find. my impression is that what is acceptable is mostly dependent on case law and interpretation by the courts. but you personally need to do your own research and learn the laws.
WA state laws - here's what i found reguarding a few of the basic WA knife laws:
(found here: http://apps.leg.wa.gov/RCW/default.aspx?cite=9.41.250)
Dangerous weapons — Penalty — Exemption for law enforcement officers.
(1) Every person who:
(a) Manufactures, sells, or disposes of or possesses any instrument or weapon of the kind usually known as slung shot, sand club, or metal knuckles, or spring blade knife, or any knife the blade of which is automatically released by a spring mechanism or other mechanical device, or any knife having a blade which opens, or falls, or is ejected into position by the force of gravity, or by an outward, downward, or centrifugal thrust or movement;
(b) Furtively carries with intent to conceal any dagger, dirk, pistol, or other dangerous weapon; or
(c) Uses any contrivance or device for suppressing the noise of any firearm,
is guilty of a gross misdemeanor punishable under chapter 9A.20 RCW.
(2) Subsection (1)(a) of this section does not apply to:
(a) The possession of a spring blade knife by a law enforcement officer while the officer:
(i) Is on official duty; or
(ii) Is transporting the knife to or from the place where the knife is stored when the officer is not on official duty; or
(b) The storage of a spring blade knife by a law enforcement officer.
Weapons apparently capable of producing bodily harm — Unlawful carrying or handling — Penalty — Exceptions.
(1) It shall be unlawful for any person to carry, exhibit, display, or draw any firearm, dagger, sword, knife or other cutting or stabbing instrument, club, or any other weapon apparently capable of producing bodily harm, in a manner, under circumstances, and at a time and place that either manifests an intent to intimidate another or that warrants alarm for the safety of other persons.
(2) Any person violating the provisions of subsection (1) above shall be guilty of a gross misdemeanor. If any person is convicted of a violation of subsection (1) of this section, the person shall lose his or her concealed pistol license, if any. The court shall send notice of the revocation to the department of licensing, and the city, town, or county which issued the license.
(3) Subsection (1) of this section shall not apply to or affect the following:
(a) Any act committed by a person while in his or her place of abode or fixed place of business;
(b) Any person who by virtue of his or her office or public employment is vested by law with a duty to preserve public safety, maintain public order, or to make arrests for offenses, while in the performance of such duty;
(c) Any person acting for the purpose of protecting himself or herself against the use of presently threatened unlawful force by another, or for the purpose of protecting another against the use of such unlawful force by a third person;
(d) Any person making or assisting in making a lawful arrest for the commission of a felony; or
(e) Any person engaged in military activities sponsored by the federal or state governments.