Function, looks or frame design ?

[jacktrades_nbk]

I've noticed that on most traditionals, from what i have and what i see around here, the blade curve in general sits lower than the handle, forming an arc with the handle, instead of a straight line.
And when the spine is straight with the handle, the shape of the blade changes to lower the tip and curve below the handle. Not always though, as the buck 110 has the spine and handle straight, and the edge parallel to the spine.
I've seen spear points that are narrow at the base and get wider towards the tip, again lowering the edge below the handle.
Opinels also have the blade at a slight angle from the handle, making the curved edge to sit lower.
The curve found in a clip point is almost always much lower than the handle spine line, and sometimes the edge is not parallel to the spine, achieving the same thing.
Either the whole blade is shaped that way, both edge curve and handle angle, or just the edge forms an arc with the handle, while the spine is straight.
Now, this curve sitting bellow the handle, acts somewhat like a recurve in cutting, increasing the force in that area, in other words, it will cut better in most cases.

Be it spey, sheepsfoot, clip point, pen/spear, they sit lower than the handle, forming that arc in most traditional knives.

Some examples :

The peanut shows this better, as the arc is formed not only by the edge and handle, but also the handle and blade spine together.

But in the queen canoe, the small pen is straight, while the big spear widens towards the tip. This is seen much better in the 2011 forum knife,
A pic from around here :

On the buck 303/301, the clip point edge forms an arc with the handle, but the spine and handle are in a relatively straight line.

So, is the better performance what dictates this design, or there are other factors, like looks and frame shape involved ?
I'm hoping maybe someone can explain this thing better, or at least that my ramblings make some sense...

 

[lutejones]

I Also thought about that several times, and I reach what I think is a very probable explanation:
When you cut over a plain surface the position of the edge lower than the hand alouds you to cut more comfortable, because if it were straight your hand will hit the table or whatever you're cutting on.
Mateo

 

[Rsmith_77]

Now that is interesting. I always thought the case texas jack was identical to the peanut, just scaled up
but I see now that they have very different lines.

I wonder what that means. They are both serpentine, but it appears the peanut is more so
they are both clip points with pen, but it looks like the peanut has a fuller clip (compared to size of the handle anyways)
weird

 

[Doug Add]

Now that is interesting. I always thought the case texas jack was identical to the peanut, just scaled up but I see now that they have very different lines.

I wonder what that means. They are both serpentine, but it appears the peanut is more so they are both clip points with pen, but it looks like the peanut has a fuller clip (compared to size of the handle anyways)
weird

I don't know the design science behind this, but I notice the same thing between the Case 6207 (on top in the photo) and the 6232:

Also between the GEC 56 and 66 jacks. Take a look at lambertiana's second photo here.

 

[Will Power]

I'm interested by this. Looking at old knives and particularly catalogue illustrations, they appear to open out straight with the spine/spring. It could be mainly single-blades though.

Certainly contemporary CASE knives often have this 'droop' is it cant? GEC patterns such as the 68 White Owl and the 66 Jack appear to open out more or less straight. So too the Queen Heritage 2011 single blades.