What is a sharpening choil?
Not to be confused with a finger choil which is an area of unsharpened metal that will prevent your finger from getting cut if your folding knife accidentally closes. The sharpening choil is a small notch that’s ground into the edge of the knife where the unsharpened and sharpened metal meet. It’s usually drilled into the knife blank before hardening, but can also be ground in with a chainsaw or round file.
With heavy use and continual sharpenings, a knife’s plunge line and bevel might begin to look a little off. The sharpening choil removes the bit of metal where this would start to happen and provides for a definite sharpening line. One of the disadvantages to having a sharpening choil or notch is that it can sometimes snag on the material (like rope) that you’re cutting. Do you need a sharpening choil? No, but it could be a good idea on knives meant for long term use.