Hi! It looks to me many inanimate objects and tools have been invented, designed and constructed by Man with the only purpose to kill other men. The first images which pops up in my mind are the Vickers machine guns and the poisonous gases employed during the WWI. Sure there can be numerous other examples. It’s very hard, for me, to imagine for these any recreational use. So, in my opinion, there are things which are, by original purpose, weapons.
Specifically when it comes to blades and knives, I also see some of these have been invented with the only purpose of being weapons; the first examples which pops up in my mind would be the daggers and the bayonets. With some imagination and some efforts in practice, though, I can figure out for these different “utility” uses (e.g. chop an onion and open K-rations).
Then there are the so called “restricted dangerous goods” or the “prohibited or restricted items”, most of us are familiar with (e.g. when taking a flight). These are not designed to be weapons but, for their inner characteristics could be more easily employed than other inanimate objects and tools to kill or wound other humans. Knives, in my opinion, exactly belongs here.
I see the legislation where I live (and in most of other European countries) tries to take this into consideration. As someone else already said, I personally would blame Hollywood (in a broader sense) only as a contributor for the ban of some specific types of knives, namely the switchblades and balisongs.
In Italy, the origins of an overall “hostility” and suspicion towards knives date back centuries; back to the times when nobility forbade the peasants to carry swords. That was a privilege only allowed to the nobles who were surely happily killing each other and did not step back when it came to pierce some peasants even for futile motives, but they did it “in style” and as “government representatives”. The peasants, for obvious practical and working reasons, were anyway allowed to use knives (albeit with many limitations already found in edicts and in the laws of the time). Soon these became the favourite “assault weapon” of brigands, stalkers, and “hothead” brawlers. The knife became literally the "sword of the poor".
Particularly in Rome, there has been an entire sub-culture who has gravitated around knives fights. In the city of the Popes, the knife was the weapon for excellence to resolve private disputes, especially within the terrible but fascinating world of the so called "Bullies".
The knife, with its ambivalence, is obviously a tool but can be easily turned into a weapon and it has been the protagonist of many bloodsheds with particular significance. In Italy, between the 1600s and the early of the '900, the city of Rome had the sad primacy for knives homicides, at least for those committed during the so called “duelli rusticani” (peasants duels, normally fought with knives).
Drawing a limit between the banned and the lawful has constituted the daily concern for the legislators in every age, precisely because of the ambivalence of the instrument and the nobility and the people alike have always tried to find shortcuts to circumvent the ever-changing laws. How not to remember e.g. the disguised knives of the sail makers or those of the saddles makers, that even had the needle eye to disguise their EDC knives as a working tool in that period? To “get to the knives”, in those ages, didn’t take that much: a second look to the wrong woman, the wine poured from the wrong side (read as an offence) or even a poor hand shake, it was just enough for the typical phrase "tira fora er cortello" (take out your knife).
I think society has evolved for the good for sure in this respect but these memories and history sort of remain ingrained in the imagination of the people. It will take time to delete or mitigate this “bad name” on knives, at least here and a lot depends on "us", the hobbyists, aficionados, hikers, etc.