This discussion, this thread, is occurring in multiple cyber-venues. Without naming the others - you can PM me if you wish to know what they are - I'll say that I just read a public post from someone on one of the others that is well-written and relevant here in terms of legalities and training. So I'll copy it in.
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Nem,
At the outset, I'll make no claims to expertise, nor list any tactical schools I've trained under, with a knife. A fighting knife, IMO, is very different from a utility knife, and one will not do the job of the other, as effectively.
[Another poster] points out one of the types of knife prohibition law, generally, which is felonious use and intimidating use (e.g., brandishing). Unfortunately, there are a number of types of laws that you should consider in order to set the parameters for knife selection. From my review, knife laws in a State or local jurisdiction, are of the following types (and there may be more, but these are what I found, generally):
(1) Prohibition against possession
(2) Prohibition against open carry
(3) Prohibition against concealed carry
(4) Prohibition against intimidating use (brandishing)
(5) Prohibition against use of a knife in the commission of a crime (whether felony or otherwise)
Any of the first three categories may have prohibitions without looking at your actions, but are based upon type (knives defined as daggers, dirks, trefoils, switchblades, auto-openers) upon blade length, or upon other explicit characteristics (double-edged blades, for example).
I've discussed this subject with peace officers (retired and current) and, I received varying answers, which, to me, were unsatisfactory. I had a po at a gun store tell me that a fixed blade over 3" was illegal, and that any fixed blade surely will be confiscated, if I couldn't answer why I was carrying it, to his satisfaction. Ironically, within a few seconds, he drew a larger AO lockblade with a clip-draw from his front pocket, and extended it to within inches of my face, and said 'this is legal', without any suggestion that the actions he took in drawing it were improper. I was dumbfounded.
On a practical note, with knives, just as wrt some guns, how would one know what you have, until it is deployed? My county has specific laws dealing with concealed carry of knives, and some, who want to carry a larger fixed blade, put it in a sheath, openly displayed on the hip, to stay legal.
Some knife manufacturers (I spoke with one at SHOT, who was very helpful), specifically make their knives a hair shorter than 3", and are confident that they will be 'legal' in most, if not all, jurisdictions (even in Europe).
After considering the legalities on-the-surface, you will find that police officers are not fond of concealed fixed blades. A fixed blade knife is considered by them a VERY deadly weapon, depending on the skill of its user, with good reason. Deployment is very fast, and people, generally, have a very visceral reaction to the presentation of a knife, perhaps more so than to presentation of a firearm.
O.K. so that's IMO a summary of types of laws you should be aware of.
Onto knife selection ....
There are many schools of thought on the use of a fighting knife. The type of martial training you have or don't have should dictate the type of knife used. To my mind there are two major classifications, the Asian sword/knife systems and the Spanish/Euro-American sword/large-knife systems, and, then there are hybrid systems (krav maga, kali, escrima, etc.). They are very different, in that the size, shape, and characteristics of the knife employed relate closely to the 'forms' of martial/hand-to-hand combat in which one may be training.
As a general comparison, Asian systems focus on contracting movements, defensive movements, very close contact with hand-to-hand-elements, blocking, and slashing, while Spanish/Euro-American systems focus on expansive movements, engagement distances, and the thrust, as a primary skill (with slashing as secondary).
I've had difficulty with where and when and how a knife will be the most effective tool, just as I've had difficulties with where and when and how a BUG is to be employed, if at all. It always 'just depends'. E.g., someone may tell you their BUG is a pocket 642, while the primary is a 1911 IWB. But why must one attempt to draw the 1911 first? I simply won't generalize about which one should be deployed first in a confrontation. Same goes with a knife. It may or may not be the primary weapon, depending on the circumstances.
Another topic is the 'ingredients' to your knife. Type of blade (tanto, spear point, recurve, wharncliffe), length of blade, materials, and other components to the blade (types and size of guard, grip and pommel, quillons, notches, etc.). There are many choices here, and anyone who tells you which is best, without qualification, is coming from a perspective of bias, usually, in part, based upon their training pre-requisite martial arts, hand-to-hand combat. The martial arts training, or lack thereof, usually has a big effect on knife selection. But this bias convinces people who have no training in asian martial arts to go out, nonetheless, and acquire a knife not suited to their background.
The knife posted by [another poster] has all the attributes of a traditional euro fighting knife. If you have experience in that style of knife deployment, it can be very effective. I have one very similar that I picked up at a pawn shop, excellent handling/manipulation characteristics, but I can't carry it concealed (it likely would be classifed as a dagger, here, and the length is over 4") in my county, so it stays home.
Know your physical limitations and training background, and how far you are willing to go, training in that style. There isn't necessarily a 'best', so I'm not going to argue Bowie (which I'd prefer, however, based on my own skill-set) over Asian systems, here.
I think the discussion of knives, even moreso than discussion of types of firearms, remains a wide-open area, despite the fact that Americans have been fascinated with and have shown a general bias toward the Asian systems for over a generation now. Knife-design reflects some of that bias. Not necessarily a bad thing, but something to consider.
