Last time I was in Gatlinburg TN every other tourist trap gift store was selling switch blades with no questions asked. And these were full size with up to 6 inch blades. What is up with that? It seems they are legal at least in that city.
The fact stores sell an item doesn't necessarily make possession of the item by lowly private citizens "legal" here in the Land of the Free. In late 1973, I bought a Bianchi aluminum baton for use in my employment as a security officer at a sugar refinery in Spreckels, CA. I bought the baton at Dick Bruhn's, a men's clothing store in Salinas, CA which also sold police uniforms and equipment. It was a year or two later while studying Criminal Law in college that I discovered it's a felony in California for a non-LEO to possess a billy club (and numerous other items). It was beyond my comprehension that merely possessing a billy club could be a crime, let alone a felony. The fact I purchased it from a reputable business would not be a legal defense in court. Judges just love to say, "Ignorance of the law is no excuse," even when they were completely unaware of a statute until the case reached them. Attempting to explain at trial why a law is unconstitutional (after the 1895
Sparf decision) is a surefire method to get yourself gagged and held in contempt of court.
Your legal-fu is strong. :thumbup:
If I had a twelve year-old child who didn't know more about the Constitution, American history and jurisprudence than every SCOTUS justice since 1913, I'd consider a retroactive abortion.
Can I call you if the DPD bust me for carrying a 3" Microtech?
Sure, if you can afford my billing rate.

It's unlikely the DPD will be enforcing the Federal Switchblade Act, but rather Colorado and local anti-knife statutes.
Colorado Criminal Code Section 18-12-101 defines a "knife" as "any dagger, dirk, knife, or stiletto with a blade over 3-1/2 inches in length, or any other dangerous instrument capable of inflicting cutting, stabbing, or tearing wounds, but does not include a hunting or fishing knife carried for sports use." One can only wonder what Colorado legislators call a knife with a blade under 3.5" since, by their definition, it's not a knife. Section 18-12-102 decrees switchblade knives are "illegal weapons" (a phrase which would have confounded our Founding Fathers) and the mere possession by non-LEO/military personnel is a Class 1 misdemeanor (possession of a "dangerous weapon" is a Class 4 felony). I didn't find any exceptions for one-armed persons under Colorado law. Personally, I regard typical ignorant, amoral voters to be far more "dangerous" than any inanimate object but that's just me.
Colorado courts upheld the conviction of a person who possessed a screwdriver, holding that a screwdriver can be reasonably construed as a "knife" under Colorado law. See
Miller v. District Court, 193 Colo. 404, 566 P.2d 1063 (1977).
And can I sue for discrimination under the American Disability Act?
You can sue anyone for anything; whether you prevail in court is a different matter. You want to use a blatantly unconstitutional federal law (Americans with Disabilities Act of 1990) to challenge an immoral state statute? Does that come under the Two Wrongs Make a Right theory of jurisprudence?

You could mention to DPD officers that you, like every other human being, have an unalienable individual right to keep and bear arms any arms, anywhere, anytime and remind them they swore an oath to adhere to the U.S. Constitution. While they're rolling on the ground laughing, you might be able to make a clean getaway.
Seriously, a single-edged DA OTF was not designed as a "weapon" . . . it was designed as a safety knife.
Lincoln High School in Sioux Falls, SD was locked down for an hour-and-a-half today while a herd of police ransacked the facility. What happened? Some students had been observed in the school parking lot with a "dangerous weapon" a plastic toy pistol designed to shoot rubber-tipped plastic darts. The students are facing long suspensions and police/prosecutors are ardently searching for some criminal offense to charge them with. The fact the toy was never "designed" to be an actual weapon is of utterly no consequence in contemporary America. When I recited The Charge of the Light Brigade to my sixth grade classmates in 1963, I held a WWI-issue Springfield rifle as a prop. No one thought anything of it. Today, a SWAT team would be summoned and a student would be lucky to survive the encounter.
Do not understand why a 3.5" fixed blade is A-OK, but a 3" OTF is verbotten.
If you expect most legislators and the armed minions who enforce their edicts to exhibit common sense and a genuine regard for the Constitution then you may as well expect to encounter a Martian or an honest, competent attorney. When the Federal Switchblade Act was enacted in 1958, it was primarily a reaction by politicians pandering for votes to the use of switchblades by actors portraying "juvenile delinquents" with such knives in movies produced in the 1950s. At the time, the Departments of Justice and Commerce actually opposed such legislation. The members of Congress who sponsored the FSA publicly admitted the law wouldn't really do anything to deter violent crime but it was a "tool for law enforcement" (a phrase which never fails to infuriate me).
Sheath knives make people nervous in the city.
The next time I willingly render myself unarmed and helpless rather than make cognitively- and/or ethically-impaired people "nervous" will be the first.