Anyone used a knife with these? Looks like they wouldn't even cut any better. Supposedly you don't need a special sharpener for them which leads me to believe you would sharpen the whole thing like a plain edge, but if this is the case the insides of the slots wouldn't be sharp and snag on fibrous things like nylon rope. Gimmick or not? I noticed them in the SMKW '03 Christmas catalog on p. 70.