Apparently I misspoke when I said that the reason one shakes hands with one's right hand is so the left hand could be ready with a sword if the hand shake didn't work out so well.
A kind reader pointed out that it's the other way around. One shakes with one's right hand to show that there is, in fact, no sword coming, since the majority of people are right handed and would brandish their swords accordingly.
I'm not sure I buy it either way. I feel pretty confident that right handed hand shaking developed because of the deep cultural roots of the left being unclean and most people being right handed in the first place. There was a time when pretty much everybody used their left hand only for...their toilette. It makes sense that people would only extend the right hand, no matter if they were right or left handed, in friendship and solidarity, if we all knew where that left hand had been.
Ironically, it means that all the left handed people were probably quite a bit cleaner than everyone else, since they were using their 'good' hand, that is to say, the hand with more dexterity.
This all reminds me of a website I found once that explains a long list of traditions and practices, like carrying the bride over the threshold (which according to some sources, also involves the devil). The explanations all made perfect sense to me. I'm pretty sure the sword one was in there.
Several people told me later that it was all untrue.
How did they know? It all sounded very plausible.
The sword thing is the least plausible explanation I have heard for a tradition. It's not like every single person had a sword. A knife, maybe, but not a whole big sword. It doesn't make sense to me that a handful of people saying to each other, "See, I'm offering you the hand that would otherwise kill you, which means I won't be killing you just now, so we can all relax" would somehow translate into an across the boards demand for right handed handshakes.
Maybe it's just me.