There are a number of the embellish a knife to personalize it or just to dress it up a bit. Here are a few examples:
Scrimshaw is an old art form developed by the whalers who would spend their free time scratching artwork onto whale bone. Bone, ivory, micarta and even corian lends itself well to scrimshaw. The art is actually small scratches and/or dots made with a very fine pointed scribe and then filled with ink or paint.
I do not claim to be a great scrimshaw artist. I can do pretty well with simple graphics and I am getting better with practice but will probably never be in the league with Garbo, Linda Karst Stone, Sandy Brady, HutcH, or a number of other full-time scrimshaw artisits.