> Anyone that isn't a professional chef is probably going to leave a little blood on a knife by cutting themselves with it.

That's a strong claim.

I'm not a professional chef but I like to use a chef's knife, and I cut rather fast. Yet I don't remember ever cutting myself to the point of bleeding. I only remember scraping off nails and skin.

> like some blood caught in the space between the handle and the blade

I reckon that if it gets stuck between the handle and the blade then we're talking about more than a little blood.