Mr. Buchanan was kind enough to lead me to this thread, so I'll post up how I take knife photos. I have been into photography for a long time, and most of this gear I did not buy specifically for knife photography. It is studio lighting and modifiers for portrait photography. But it turns out to work pretty well for both.
The flash head is an Einstein E640, with a Mola beauty dish installed on it. And I put a diffusion sock on the dish. I then shoot that through a translucent disk that is part of a Wescott 5-in-One Recflector kit. The intent is to spread the light out, make it softer, and provide a white material to reflect back off of the knife blade.
This shot was taken with a Canon 1DMkIV, 24-105 lens.
1/100 shutter speed, f/10 aperture, 200 ISO.
I use Photoshop CC to edit my photos, and consider some sort of photo editing software a MUST to get the most out of your knife pictures.
Well, here are the pics. Hope they help a little, and if there are any questions I'd be more than happy answer.