I have long understood that the right-handed shake evolved from most people being right-handed, thus handling dagger with right hand, thus extending right hand = no weapon at the ready. And similarly, that Euro at-the-table habit of leaving wrists upon the table--whereas I from New England was taught to rest them under the table, in my lap--was indication of no weapon in hand. I've been reading Old Testament, and note that twice in Kings and Chronicles, a pointed point was made that a particular group of guys was equally skilled with left and right hands. The point was made.