Knives are created under the Self > Skills > Carving > Knifes... menu. The Carving skill is required. All Knives appear to be capable of performing all task categories under Carving (From Basic to Advanced), but each use costs a certain number of uses of the knife - and higher-tier knives have more uses before they break, or in the case of sharpenable blades like the Utility Knife or better, needing to be Sharpened. Additionally, slaughtering Cows requires a Flint Knife or better and slaughtering Pigs requires a Bone Knife or better. Slaughtering Cows and Pigs consumes a relatively high number of uses of a Knife.
Knives may now be made of a variety of materials, with more advanced materials having a higher base durability (number of uses) before breaking or, in the case of Utility Knives or better, dulling to the point of needing to be sharpened.
The Stone Knife is simple, cheap, and flimsy. It will break quickly even if used for Basic tasks.
A Stone Knife can be used to kill 3 Cows before becoming dull. Afterward, the same knife may still be used to make 9 Sharpened Sticks (Novice). Or 4 Barrel Taps (Skilled). Or 1 Empty Tackle Block (Expert). This is a cheap way to manage your cattle, as this knife does not first require a knife to make the required components.
Requires: Carving 2
The Flint Knife is slightly more sturdy than the stone, but still breaks quickly, especially when used for slaughtering animals.
Requires: Carving 3
The Bone Knife is slightly more sturdy than the flint, but still breaks relatively quickly when used for advanced tasks or slaughter.
Requires: Carving 4
The Utility Knife, made with a good-quality blade, is considerably more sturdy than the Bone Knife. An 8500Q blade lasted at least three times as long as a Bone Knife when slaughtering Cows. Increased quality of the Sharp Edged Blade used will increase the maximum durability (number of uses before dulling) of the knife. A Q8500 Utility Knife can sharpen exactly 200 sticks before becoming too dull to perform Basic tasks.
Unlike the earlier knives, Utility Knives may be Sharpened. They must be unequipped to be sharpened, and then may be sharpened under Carving/Sharpening. If the knife is still good for tasks, you will be warned that the knife is still capable of some form of task before sharpening. This warning will appear if you have only used the knife to slaughter animals, even at the point the knife is too dull to slaughter animals. Once sharpened, the knife will have its maximum durability permanently decreased, but have it its present number of uses remaining set to that new maximum, allowing it to once again be used for more complex tasks.
Sharpening can be repeated when the knife once again grows dull. The apparent loss in maximum durability appears to be 5 Basic uses per sharpening - a knife capable of 200 Sharpened Sticks pre-sharpening was capable of 195 after sharpening, and 190 the sharpening after that.
Requires: Carving 5
The Paring Knife functions as a knife. It may or may not be more durable at the Data on whether this is actually the case would be appreciated, as high-quality Jagged Edged Blades are hard to come by. The ability to slice veggies into forms that may be cooked appears to be unimplemented as of yet. This knife can be sharpened.
Requires: Carving 6
Butcher's Knives are supposedly better for slaughtering animals than other knives, losing less durability, but haven't been able to confirm if that is implemented yet. A likely Q2700ish Twice Folded Blade allowed for the slaughter of 14 Cows, mostly calfs, before running dull. This knife can be sharpened.
Explanation of the System, for Reference
Additional explanation of the new knife system from comments from Apophis on Discord 8/1/2018:
"Stone knives are now made with Slate Blades.
They don't last very long, and can't be sharpened.
Flint knives work about twice as long as stone knives, and cannot be sharpened.
Bone knives work about three times as long as stone knives, and cannot be sharpened.
Utility knives are made of sharp blades made out of metal, and last as long as bone knives, but can be sharpened, and a higher quality blade will give it even more uses.
Paring knives are the same as utility knives, except that they will also allow you to cut veggies into slices that will be usable in cooking recipes. They'll multiply your veggie yield, in practice.
Butcher knives are the same as Utility Knives, except they are not worn down as much slaughtering animals. You can kill more animals with a butcher's knife than with a utility knife.
Ancient Knives... well, I guess you'll find out when the time comes."