German-style shears have non-honed, beveled blades. “German-style” and “beveled” are interchangeable terms. Beveled shears produce a crisp cut, are durable and exceptional for dry and taper cutting, pretty good for wet and point cutting, and poor for slide cutting.
Japanese-style shears are honed, convex blades with a very sharp, more delicate edge. “Japanese-style” is synonymous with “convex”. Convex shears produce a softer cut, are exceptional for slide, wet and point cutting, very good for dry cutting, and pretty good for taper cutting.
A convex blade is slightly harder to sharpen and takes more time to finish thus being more expensive.
How I sharpen shears
I treat every pair of shears with extreme care, and full concentration. I understand many people have shears that cost hundreds. I use a flat-hone machine designed to sharpen shears. The machine uses sandpaper disks from 800-3000 Grit. Additionally I use a cushion, and a wool disk coated with a diamond emulsion for honing and polishing convex shears. I adjust the tension if necessary, and test them with real hair to make sure they cut well.