It's definitely not buying function. If a guy wants to buy a piece of art, that's totally up to him, of course...but I'm not much interested in pretending that a guy who bought a piece of art ALSO bought a superior tool.
A Van Gogh would be cool to have...but I wouldn't tell people that the canvas it was on was a better bullet stopper than kevlar, because that would make me retarded.
So it really just depends on what your friend's reasoning was on buying the knife. If he thinks it is better at cutting than a $10 mora...buy him a pair of velcro shoes.
Full disclosure: I'm the editor of Calibre Magazine, which is Canada's gun magazine. In the past I've done consulting work for different manufacturers and OEM suppliers, but not currently. M4C's disclosure policy doesn't seem to cover me but we do have advertisers, although I don't handle that side of things and in general I do not know who is paying us at any given time.
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