About the hole affecting the strength.
Sure, prying will eventually break a knife, but very rarely at the Spyderhole location
That depends where you're prying with the blade. If you're prying with the tip, then yeah, the tip is going to break. If you're prying with the body of the blade, then the crack is going to propagate through the weakest point. Where is the weakest point? Is it through the body of the blade, or through a giant hole in the blade?
Come on, guys, this is simple physics/materials...
The hole is at the part of the blade where the blade is both thickest and widest.
I know you mean from spine to edge... But consider two potato chips: one is very skinny, and the other is wider. There isn't going to be much difference once you put enough stress to break them.
Also, if the potato chip had a hole in it (lol), then where is the crack most likely to appear?
The problem is that with a folder, if you think about it, they ALL have a hole in the blade which diminishes strength. It is the hole through which the pivot pin travels.
That's actually less likely to be damaged for a number of reasons:
1. The hole is in the thickest part of the metal. The pivot's depth is the size of the full thickness of the blade (say 3mm for a 3mm blade). The deployment hole is much bigger in diameter, and if the blade is flat ground, for example (as was the Military), then it is less deep. You know that when something bends, one side of the material compresses while the other expands. It's harder to cause this to happen with a thicker material (the pivot area vs. the deployment hole area.)
2. As you mention: torque.
τ =
F x
l. Your pivot hole is in a position on the tang such that you're not going to be able to apply a lot of force at a great distance (l). You're not going to get that much torque. If you consider applying from the other side, then it should be obvious that the deployment hole is going to break before the pivot hole.
3. The pivot pin and handles are going to break before the pivot hole does.
And I'd like to restate: this is merely a technicality. If you're using a knife as a knife... then you shouldn't even have to worry about this.