As a kid, for some of us of a certain age, jackknives/folding knives were all straight edges. You could trim and clean your fingernails, peel an apple or potato or even slice a tomato right out of the garden. Practically every adult and most kids in years past carried a jackknife, or what was called a pen knife in some cases. Kids even carried them to school and cut up their apples at lunch and played Mumblety-peg at recess.
Certain jobs require certain knife blades and you may have had to carry various knives for specific cutting jobs for your work, but the knife you carried everyday was used to cut your meat, peal your fruit, cut string/rope or you could field dress small game or even clean fish.
Today you have choices. You can buy a full serrated blade, a full straight blade, or a combination of both. Do you need a serrated edge, do you want a serrated edge?
A serrated edge has a place, but the applications are more defined. You can peel an apple with a straight edge, as well as, cut heavy webbing, rope, vines and so on. Albeit, cutting heavy nylon webbing or heavy rope with a straight edge would be more difficult than with a serrated edge. The point is you cannot peel an apple very well or at all with a serrated edge without making a literal mess out of the job, so certain blades have specific jobs at which they are better suited.
Rescue tools used by first responders are blades adapted for a specific purpose. Firefighters and paramedics may have to cut someone out of a seatbelt, for example, so a serrated blade works well for cutting heavy materials such as nylon or heavy canvas webbing.
The serrated edge grips the material unlike a straightedge that may slip when starting the cut and it may even require two hands to complete the job. You cannot saw very well using a straight edge, but then again, you cannot whittle or carve wood with a serrated edge very well, so there you have it.
Military knives are adapted for specific purposes as well. Pilots and other aircraft personnel have specific blade requirements if they have to bail from their aircraft. They may need to cut themselves out of their parachute harness if they get hung up for example.
A serrated edge works well, because in many cases, you can do the cutting with one hand, because again the serrated edge grips the material. You do not have to hold the material with one hand while cutting with the other. This is important, because one hand may be injured, or you simply cannot do the cutting with both hands. The knife has to be such that it can be drawn and used one handed, so the edge has to be able to do the job with as little effort as possible as well.
It almost seems like today that you have to go out of your way to purchase a straight edge blade, because they all seem to be a combination. Fifty percent of the blade is straight, while the other 50 percent is serrated, so the best of both worlds right. Well now comes the sharpening, you know how to sharpen a straight edge, but a serrated edge, well it could be tricky, so maybe it is best to just leave it be until you figure it out.
A serrated edge if it is quality steel will hold its edge much longer than a straight edge because for one thing it is not used as much, and two; the scallops are protected by design. Many knife sharpeners on the market today come with a tapered diamond rod that is ideal for touching up the scalloped edges. A fine rat tail file would also do the job, but you would have to be careful not to remove too much of the metal from the blade.
Serrated edges are nothing to be leery of, and they do have a purpose, but does the edge fit with your cutting needs.
Bread knives are typically serrated, because they grip the soft bread and allow for a sawing motion without crushing the bread. You could in theory cut the bread into slices with one hand. You could never do this with a straight edge.
Serrated edged blades can take more of a beating, because the sharp scallops are somewhat protected. When was the last time you sharpened your bread knife that has been tossed around inside of your kitchen drawer. The edge is being banged against all manner of metal objects in some cases, as you rifle through the drawers. Electric knives are typically serrated, and you cut all types of foods with one, and again when did you last sharpen it.
This article is not advocating for or against serrated edges. In fact, past articles have railed against them, because people buy them without understanding the why.
You cannot use brute force to make a dull straight edge do its job, whereas you can use force to make a serrated edge do the job without the blade slipping and cutting yourself as easily. The dangers of using a dull straight edge are obvious. A dull straight edge will slip, and a dull blade can still slice your finger to the bone.
The obvious answer is to carry one of each, or a quality blade that is a combination. A cheap blade will provide sub-standard performance, so if you have a job that requires your knife always be ready then you will have to step up and buy quality.
People usually have a so-called beater knife, stuffed inside a pack, the one you go to pry rocks, dig small holes, and generally abuse, because it was cheap and can be easily replaced. However, that beater knife may not cut you out of a seat belt, or cut heavy cordage or even cut up your food for supper.
You do not have to spend a fortune on your knives however. A quality knife can be bought for well under 100 dollars, but paying 10 dollars for any knife means you will only get 10 dollars worth of use out of it. Shop around and ask around, but also make sure the person you are asking actually uses their knives, and that they know why they have certain edges on their knives.
People buy knives just to have them. They look dangerous, so oftentimes a knife is bought for its looks. Take the so-called Rambo knives made famous by the Rambo movie franchise. The knife is wicked looking, and how neat is it to have a survival kit in the hollow handle. Sew up a wound, start a fire with matches in the handle and cook the fish you caught with the hooks, line and sinkers all stuffed in the hollow handle as well. You may be taken hook, line and sinker if you spend any serious money on this type of knife however.
When hollow knife handles can brew a fresh cup of coffee and produce lunch then maybe you should consider one, but until then, buy for quality and job needs not for looks.