what do you look for in a fighting knife?

I am saying that in order to carry a weapon in public - in theory - you should be mentally checked based on the slogan "guns don't kill people, people kill people". Now, if for you a ballpoint pen is a weapon, it is another story. Too many ninja movies or just stating absurd things to dismiss the real problem? 

I think that if you want to kill someone, you will do it. It boils down to common sense, that's a rarity these days. Most of the laws are based on common sense. 
Give me a reason to wear a short sword going to groceries. Why would you? Are you afraid for your life? Big bad pumpkins are watching you? It makes you feel more secure? Or just because you have it you are entitled to use it? 

I think you either missed or ignored my point entirely. And I disagree, weapon laws in the United States make no sense to any but the fearful and those that don't believe in the principled laws set forth by the Constitution and Bill of Rights.
I didn't say dueling wouldn't be a problem,(it would be a rare thing) I was asking if it currently was one, to make a point..and if you think everyone would start dueling if swords were legal to carry, you probably also believe that everyone armed with a handgun wants to live in the wild west, so I won't go any further with that.
By the way, I see you're one of these people that worry about people taking your stuff.. you've lost before the fight has even begun, so why have anything? Some big bad criminal might come and take it, because they want it..I have lots of nice stuff. I've carried a handgun for 20 years. Nobody's ever taken anything from me. Nobody ever will. And hell, if they manage it, I probably won't be around to see it. And by the way, the majority of theives ARE weaponless, a very large majority. At least, that's been my experience. Any law enforcement reading this? Am I wrong? Maybe I've lived a sheltered life, lmsao!

Back in the time before young children devoured every waking moment not spent toiling for bread and circuses, I would somewhat regularly hunt to fill the larder with sweet venison morsels. Here in Texas, we have some of the most restrictive knife carry laws in the union, but under most circumstances they are rarely enforced (at least for those of us fortunate enough to be born into life's easy mode). I would always carry a couple good skinning knives (always within the legal carry size), and also a large knife capable of cutting bone (field dressing game), slitting throats (euthanizing injured game), and any other uses in the field that may call for a sturdy blade. The knives have always been larger than the law allows, but I have noticed that most hunters in South Texas are either unaware of any knife restrictions, or are unconcerned about their enforcement. Over the many years of hunting, and subsequently dismantling, human-sized game I have used a number of field knives of various shapes and sizes. My observations have led me to believe that minor details in size or form are pretty insignificant when it comes to dissecting animals. Toughness and edge retention are pretty high on my list of requirements, as are enough mass to chop bone and enough point to penetrate hide. I think using what you are familiar with is fairly important. I would hate to get in a knife fight with a butcher.

Your right on the "theory" thing, but (as you probably know) it ALWAYS breaks down in real world application with the "Show Me Your Papers" Orwellian police state ending.  NO WAY will bureaucratic statist politics NOT be involved in these "so called" tests, paperwork, history, etc...add infinitum. 

I understand what your saying, but the background check (computer database check for criminal activity before purchase) on firearm purchases would simply be impossible in stopping felons from purchasing large kitchen knives and such (or simply making them), as it is just too basic.  Now, we already have knife laws (just like gun), so it comes down to carry laws, and with me (my opinion) being on the side of illegal USE...if you break the law with anything USED as a weapon, you should be dealt with accordingly. 

"I would hate to get in a knife fight with a butcher"...I have to remember that one.

Well, yes, the "trap" as you call it, is indeed the human condition.  The human condition is a fascinating topic (and we are meandering, I suppose), but the questions are still interesting.  The 'State of One' probably happens when we die, with either a unifying afterlife...or blissful nothingness.  I view the society thing as (at best) governed loosely by common sense, as the more power/control/resources given to the STATE, the less there is common sense.  Back on topic, legally, the best "fighting" knife would be determined by legal environment, with the longest, sturdiest blade legally possible, and ideally a fixed blade rather than folder.  The fact that some states allow a firearm for carry, but not a blade of greater than 5" or so length is archaic and silly. 

To ban other weapons makes much sense to the sellers of firearms.   
A lenght limit to knives for allowed carrying is based on the common sense, that a longer blade isn't usefull for a tool-knive any more and makes it a weapon.
The same with a second edge.