Sandpaper. And don't stop until the black is all gone.
How far you go toward fine grit is up to you, but I used 220 grit which left mine with a relatively unpolished surface. Sharpen to taste.
Why? I disliked the "tacky" (= tactical) look of the painted blade, which is totally unhistorical for a Kephart. I'm not a fanatic, but if I have a historical pattern of knife, I prefer it to look as much as possible like its original.
Like all carbon steel blades, it will develop a patina in use. But for fast patinating, get a tall glass jar, fill with ordinary vinegar, nuke it for about 30 secs (until it's almost too hot to touch), then immerse the blade. Pull it out and rinse when the patina reaches the level you want. In hot vinegar, the process goes
fast, so be ready.
The Nessmukian Trio: Bridgeport hatchet, Camillus Army Engineer's knife, Kephart