So just cause I am interested in old shit ....
In the Japananese tradition, there has never been a greeting hand shake. However as a means to stop another Samurai from drawing his Katana another Samurai woudl grasp his hand and thrust his "web" (abductor policis) into his Ukes hand there by disabling him from drawing his sword.
Also in Ninpo; Ninjitsu; Taijitsu (or whatever you want to name it) techniques there is a draw (forbidden by many Iaido) which uses your left hand with a reverse draw (remember the blade is always facing up) turn your back to your uke and thrust a killing strike all while holding his hand to stop him from drawing his own blade.
When the round eye came to Nippon and started to study hand to hand Jyujitsu styles the noticed that some Japanese would start techniques from a hand grasp that looks remarkbly like our european hand shake.
So next time you see a traditionalist Japananese arts Sensei doing a demonstration or teaching a technique from a hand shake ... ask him "why would the Japanese do a technique from the hand shake if they bow??"
- rememeber common sense is the antithesis of all TMA -