My experience is that Burncycle has got it right!!! Those carbide sharpeners (mine are swiss made) beat out about everything, especially if you're already carrying the carbide to keep a working edge on your machete. As mentioned elsewhere, the spine of most bushcraft knives are already dressed to do the job, and virtually any SAK saw blade will really shoot some sparks. But your personal experience may differ....
Good luck,
Doc
Good luck,
Doc