I don’t know anything about Freemason handshakes, but, I shake hands this exact same way. The reason I do so is because guys usually squeeze pretty tight when we shake hands. It’s some kind of ego or dominance thing to squeeze hard enough to get the other guy to wince or show some kind of reaction whatever. When you shake your hand, if you extend that index finger straight out (it’s even easier with two fingers straight out on their wrist), no matter how hard they squeeze, they really can’t crush down on your hand. They can squeeze as hard as they want and the way your bones are supporting each other in that position, you won’t feel shit. So now, when I meet other people that want to do the dominance thing and try to squeeze my hand as hard as they can during a handshake, I’ll just stand there all day and smile while they squeeze and squeeze and get nowhere.

I know this probably sounds stupid, but seriously, try it.