I am writing a fantasy story set sometime in the middle ages, maybe a little earlier like 500 AD, and I would like to know the cheapest metals for knives. These knives would be 'belt-knives' rather than combat knives, used for cutting plants. I know bone daggers are relatively easy to carve, but they look weird and in addition the dagger needs to go into a 'sheath'. The sheath would be carved out of wood since the main character's relative is a woodcutter and wood is easy to come by. I googled 'cheapest metal' and 'bronze versus copper versus and only got the following tidbits of information: -Iron was the cheapest and most abundant metal during Middle Ages -Bronze is harder and less brittle than copper/tin since it's an alloy of both -Copper was commonly used in BC until iron replaced it since it was cheaper to make That's pretty much it. Basically I need to know what the cheapest metal out of bronze, copper, and iron is. Extra information that could prove useful to be but i don't need at the moment: -Any books in the library that detail the process of smithing and forging of ores into metals, and also where metals can be found and mined (I know Paolini in Eldest (or was it Brisingr?) researched heavily on blast furnaces so he could tell how elves forged their swords. I'd just like to know where I can find information on this since my character might later visit a town blacksmith so it'd be useful to know what tools he uses and basically what he does.
There's no one answer. If you live on top of an iron mine, with the nearest copper mine 1000 miles away, iron is cheaper. If you live on top of a copper mine with the nearest iron mine 1000 miles away, copper is cheaper. If you need your story to be set in the real world, you'll have to research, in detail, where your characters are and what the most abundant ores are there. But if it's pure fantasy, go ahead and use whatever metal you want, and just tell the reader that that one's the cheapest. Or best for whatever reason ... maybe in your culture, bronze is considered holy and iron is evil or something. Use your imagination.
What about using flint if it is readily available? Woodcutter can make it himself. It is durable and deadly.
Just adding to this. Knives/swords/sharp things can also be made out of bones, animal teeth, and even obsidian glass. The Aztecs actually had an elite warrior class titled, Jaguar Knights. They used wooden swords edged with obsidian glass taken from volcanoes. It made for a very sharp sword. Wasn't the best for blocking attacks with, but that's what shields are for.
There's no such thing as "cheap metal" in any realistic medieval setting. Seeing as it's fantasy, you might as well borrow from what's already around. Currency wise, it goes Copper<Silver<Gold. Weapon/tool wise it's wood<stone<copper<bronze<iron<steel Wood is the cheapest because it literally grows on trees, is easy to craft but is broken from use almost immediately (blades don't stay sharp, shafts break, etc.) Stone is the next cheapest because you can just pick up any sharp or heavy rock and attach it to a stick. More durable, but extremely brittle and difficult to carve - flint tools would shatter very easily. Copper is the common but soft and therefore makes poor quality tools. It's not that it's abundant, it's just that nobody wants it. Copper smelted with tin plus some other stuff makes bronze, though widespread creation and use of bronze died out well before the "fantasy" era began, so it's highly unlikely that anyone used it. Bronze was harder than copper, softer than iron and required the use of arsenic when forged, which is why the god of metalwork (Hephaestus) is depicted as lame - arsenic poisoning. Iron - and it's alloyed counterpart, steel - are the most common metals in the traditional fantasy age, though commoners would rarely have any iron implements, let alone weapons in their possession. An iron dagger would have to be either found or stolen. Bone is typically utilised by more "barbaric" cultures and has distasteful and primitive undertones. Maybe you're looking for that kind of thing, though. Just some food for thought.
If the story is set in the real world, I think iron would be best. If the story is set in the fantasy world, apply the Sacred Rule of Metals in a Fantasy World, that is, Mythril is always either the cheapest, most lousy crap in the universe or something that the maker of the ultimate sword of cursed doom would be elated to have.
Does it matter what the knife is actually made out of? If it's just a knife that the character uses for certain tasks that just about any knife would accomplish, wouldn't it be just easier to leave the metal it's made out of? Unless its either bone or one of the more valuable and expensive metals(like say Mythril for example) then I don't really needing to be mentioned. If it was bone and the use for it was part of making something(like the character is a healer or whatever) then it might be an interesting thing about the practice. If it was Mythril and the character comes from a rather small community, then it would be interesting to know how the character obtained such a fine knife. But if its neither of these, and its just a knife, then I would have left the type metal out of it. But thats just me.
Why does it need to be metal? A lot of BC cultures used other sharp materials, Obsidian was used in the middle east, Jade tools were also used (though rarely) for carving and cutting in Mesoamerica, string saws were also common in primitive cultures. Also, what kind of plants are we talking? If we're talking something rather flimsy an edged stone could work.
