These knives are held upright when used to cut leather. Cutting upright is a common tradition in Japan and Korea because the technique produces consistent straight cuts. They feature a specialized handle for holding the knife in this position.
The wider blades make straight cuts easier while the narrow blades help with curved cuts. The diagonal blades help to position the knives while upright and make them easier to modify the blade engagement.
Note that for upright knives the right/left bevel is as follows: