To the uninitiated, feather sticks might sound like some sort of traditional art project, and that's actually not too far from the truth. A feather stick is a piece of soft wood which has been carefully shaved into an intricate nest of paper-thin curls. While they are pleasing to the eye in an almost artistic manner, these carved sticks have a more important purpose: fire-starting tinder.
The key to a feather stick's effectiveness as fire tinder is its surface area. A tree branch won't take a spark easily, since it's a thick and dense piece of wood with low surface area. By carving that same branch into a cluster of dozens of fine shavings, it's much easier to nurse a small spark into a healthy flame. It's the same principle that applies to birch bark strips, cat tail fluff, yucca stalks, and other natural low-density tinder materials. They're thin, light, and have many crevices to catch an ember.
However, carving a feather stick isn't necessarily as simple as it may sound. It requires a precise angle, careful pressure, and a smooth piece of wood.
Your preference in knife design is also important — a thick and heavy blade with an obtuse grind will present challenges, especially if it's not razor-sharp. The following video from Black Owl Outdoors shows how to carve feather sticks, and discusses the impact of different blade grinds and cutting angles: