The following is based on my own research is not legal advice. Consult your own attorney.
Police are supposed to apply the law strictly. If a 4 inch blade on a folding knife is legal, then the PRESUMPTION is that any folder with a 4-inch blade is legal, even if it is called the "Man Killer."
Most states do, however, have a catchall for "dangerous," "threatening," knives, and this catchall, in reality, provides the police with a reasonable justification to confiscate most folders or charge you with a (typically) misdemeanor for possession. It would then be up to you to go to court, etc., to get your knife back or clear your name. Even if you're cleared or get your knife back, it is a LOT of trouble, IMHO.
DO NOT get into a fight -- sober or drunk -- if you have a folder on you. Use your feet. Only use your knife if you're at the point where you are justified to defend yourself (or someone else) with lethal force. You are justified to use lethal force in most jurisdictions if there is "an imminent threat of serious bodily harm." So use your knife only to save your life or someone else's life.
On a happier note, remember that in all states, officers do not have the right to search your body or your vehicle without some sort of cause (I'm not going to say "probable cause" because the standard is lower in some states). But, if the officer sees something in plain sight, and it looks like it could reasonably be a weapon, he can search you or your vehicle. Often, this means the WHOLE vehicle or your WHOLE person.
So...my point is that if you're a law abiding citizen (which I assume you are) carrying around a 3.5 inch folder called the "Skirmish" with a wide, recurved blade, it might be wise to remove the clip and carry it inside your pocket. If you're worried about a random search, make sure that the folder does not look "lumpy" in a pair of tight jeans or thin trousers, as a "lump" gives an officer "cause" to search.
Practically, though, so long as you're not brandishing your knife while drunk outside a bar, or it's not sitting on your dashboard when the officer pulls you over, you should be fine. Cops have better things to do than run random searches for pocket knives.