1. Let the reader take a pencil in hand, close his eyes, find the most comfortable position for his wrist, open his eyes and look at the two angles of the pencil in relation to the extended line of his forearm.
The pencil should cant upwards at about a 36 degree angle and outwards at about an 18 degree angle.
2. Let the reader take a pencil in hand, look at something across the room, close his eyes and point the pencil at the object across the room, open his eyes, and notice where the pencil actually points.
3. Let the reader imagine himself a world class gymnast, able to do a handstand with one hand on the point of a knife; imagine a perfectly straight knife; and, in comparison, imagine a knife with a 5 degree cant inwards, towards the inside of the forearm.
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In the best of all worlds, a thrusting dagger such as the Gerber MkII would have a 36 degree bend in the edge axis and an 18 degree bend in the flat axis; the direction of the 18 degree bend would make the knife either right or left handed.
The apperance of this knife would freak everybody out, until they held it, and it would not lay flat against the body or the leg of the person carrying it.
These bends, optimized for thrusting, would improve the backhand slash, improve the forehand draw cut, decrease the forehand slash, and yet come close to giving the blade a modicum of hacking ability, as in a featherweight Kukri.
The 5 degree bend in the flat axis represents the most that Gerber thought the typical buyer's awareness would accept or carry.
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A thrusting dagger corresponds to a broadhead arrow.
We accept the fragility of the broadhead arrow because we understand its design purpose to create a wound channel in soft flesh, and that we cannot use a broadhead arrow as a general-purpose tool.
A wasp-waisted dagger cuts going in and, because the wound internally conforms to the waist of the blade, the wider fore-portion cuts again on withdrawal.
Additionally, one can think of the wasp-waist in terms of aerodynamic or hydrodynamic drag.
We want the wide fore-portion of the blade to penetrate as deeply as possible, and so we do not want any unnecessary drag behind the widest point of the blade.
Therefore, the blade "falls away" after the widest fore-portion passes through the opening of the wound.
Think aerodynamically.