Flint knives | AskHistorians Archive Observer

Flint (and stone in general) is brittle. A long thin piece of stone swung at speed is likely to break when hitting something - a stone sword will probably not last very long in use. Thus, stone knives tend to (a) be much shorter than swords, and (b) not be swung at high speed. Stone knives can be useful tools, but don't tend to make great weapons. The classic Stone Age weapons include the spear (sometimes with a stone point, and often with a wood or bone or horn point), the bow and arrow (again, sometimes stone points, and often wood, bone, or horn), the club, the mace (a club with a stone head), the axe (with a stone head), and the sling (for throwing stones).

The stone mace and axe have stone heads, but wooden hafts which are much tougher than a stone haft would be. Their heads tend to be quite thick. If a stone sword was made as wide and thick as a stone axehead, it might survive use, but it would be excessively heavy (thus the popularity of the club - tough and often light (and therefore fast)).

Sharp edges are useful in weapons. A sharp weapon can do more damage with less effort than a blunt weapon. Many clubs have narrow edges in order to increase the effect of blows, but these are far from being knife-sharp. Swords are one way to combine toughness with lightness and a sharp edge. It can be done with stone and wood, by putting small stone blades to form an edge on a club, such as the Mexican macahuitl, discussed in https://www.reddit.com/r/AskHistorians/comments/cm6cvz/how_effective_was_a_macuahuitl_against_spanish/ or by using shark teeth for the edge:

https://collections.tepapa.govt.nz/object/85957

Both stone-edged and tooth-edged clubs tend to get damaged in use - tougher edges are desirable for weapons that are swung at speed. Thus, the sword.

There are some quite long stone blades out there, with lengths of 30-50cm. The longest I know of exceed 70cm. These long stone blades include flaked blades and ground blades (e.g., Korean ground and polished stone daggers). It is quite possible that most of these were made for show rather than for use as weapons. Some appear to have been made in imitation of (very expensive at the time) bronze weapons. Many of these long blades, especially the shorter ones, would be quite usable as knives, but would be best used by placing the edge against the thing to be cut, and slicing (in the same way that a ceramic kitchen knife can be used for slicing without breaking). Generally, these long blades are not everyday knives, and even if functional as knives and intended for cutting, were made for the elites. For everyday cutting, a simple stone flake can work very well - it can be made quickly with a single blow on a prepared core, and used for, e.g., butchering, as one would use a razor blade held between thumb and finger. When the edge loses its sharpness, it can be discarded and a new flake struck from the core. (Flakes were often thought of only as waste material from making stone tools. Many flakes, but no recognised tools, were found at some Paleolithic butchering sites. Obviously, thought the investigators, the "cavemen" doing the butchering had made their tools on the spot, used them, and taken them away with them. OK, put the flakes back together like a 3D jigsaw puzzle, and make a cast of the interior, and the tool will be revealed. Assembly showed that in many cases, it was only flakes, with no other tool. The flakes were the tools, razor-sharp disposable butchering knives.)

A nice collection of photos of fancy flint knives (some with gold-plated handles) can be seen at http://lithiccastinglab.com/gallery-pages/2012septemberpredynasticknivespage1.htm

Some extremely long blades: http://www.lithiccastinglab.com/gallery-pages/2008februaryduckrivercachepage1.htm

A curved flint sword imitating a bronze sword: https://www.researchgate.net/figure/Flint-scimitar-355-cm-from-Favrskov-on-Funen-bronze-and-flint-short-swords-both-43_fig4_321695571 - a bronze original (and perhaps the other side of the same flint sword) can be seen at https://en.natmus.dk/historical-knowledge/denmark/prehistoric-period-until-1050-ad/the-bronze-age/the-roerby-swords/

Interestingly, the above also includes a composite flint-edged wooden sword make to look like a bronze sword.

Korean stone daggers: https://web.archive.org/web/20070707205156/http://museum.kma.ac.kr/kor/museum/a1.htm

As already said, many or most of these should be thought of as prestige objects, rather than weapons intended for use. In some cases, even more extremely elaborate examples of the knapper's craft have been found: https://commons.wikimedia.org/wiki/File:Maya_eccentric.jpg - sharp edges aplenty, but not a weapon, as it wouldn't survive use.