OK, first off, the "weapons use" rules for pulling a knife are more or less identical to the "gun rules".
But we're not talking about that here, are we? You're sitting at a park bench, you go to peel an orange or whatever, and somebody freaks.
You should take it as your responsibility to avoid freaking anybody out. It's a pain, but them's the breaks. I carry something even wilder than a Strider, so I also have a silly little keychain knife (Swisstech Utilikey) on me. If I think somebody around me is liable to get scared, the Swisstech comes out instead of the Sifu.
Second, a lot of this is about surroundings, and your "looks".
All of the following can magnify your personal "scariness":
1) Your age - late teens is the worst. It sucks, but...what can you do?
2) Your race. This REALLY sucks. It shouldn't be the case, but it is. Sigh.
3) Your gender. Chick pulls out a battle blade to slice cheese for a sandwich, everybody just grins, unless she's REALLY punked out and looks pissed
.
4) Your clothes. Could you get mistaken for a gangbanger? Or a bum? Or are you doing the "armed gentleman" look? It matters.
A Leatherman Micra, Swisstech or micro-size SAK are all less than $20. In the days when blades were primary weapons, it was VERY common for armed individuals to have small non-threatening utility/food knives on their persons to avoid possibly lethal confusion as to intentions. The Bushido did this, the Ghurkas had the small knife in their Khukuri sheath, examples can be found all over the world for the same basic reason.
There's no reason we can't do the same. As a bonus, your "fighting edge" will stay sharper.
(Sidenote: The cultures that didn't do this often had built-in systems of signals/manners that made some places "no fighting zones" that nobody would ever think about violating. Part of the Native American "peace pipe" tradition was that around the campfire, it was a no-fighting zone and hence you could haul out your "weapons" to cut up dinner with no problems. Not all tribes, of course, but a lot of 'em did this. "Hospitality rules" of this sort or similar were common, esp. when nobody could afford more than one knife - Bedouin "tent hospitality rules" are probably a variant.)
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So what do you do if you forget the small knife, use the big one for utility, and somebody goes "eek"? A sense of humor is a GOOD thing. God knows it's happened to me. I was waiting for a bus a couple months back, and couldn't get the plastic-wrap off a beef stick apart
. So I get frustrated, discreetly (or so I thought!) pull the Sifu, and solve the problem. Look up, and there's this dude standin' next to me, says "Daaaamn, you gots you a SHANK!". I just kinda grin and chuckle, he's OK.
As to the law? Proving intent is a major part of any crime, and if you've got apple peel or similar around, it's not hard to explain and apologize for scaring somebody. What happens then varies all over the map by individual cop and to a lesser degree, by department. Can you stay calm, apologize, explain what happened and not come off like a nut? You'll probably be fine. Cops may "verbally prod you" to see if you'll blow up in a hurry, in which case it's cuffs time or they take your knife. They'll snarl something like "waddya need THAT for!?". It ain't that they're necessarily anti-weapon (although God knows it's possible), it's that they're anti-short-fuse-nutcase-with-a-knife. Keep cool, understand what they're doing, don't get beligerent or sarcastic about somebody getting scared and you'll be fine.
But: if this happens too often, the odds will catch up to you.
