Most Jujitsu throws and redirections directly have their origin in edged weapon conflict. It is actually quite easy to throw someone using an edged weapon. The "empty hand" was the logical extension of an armed warrior.
Think about it for a moment. If you had your choice; cut and let the opponent stand there and re-cut you, or develop techniques that cut while de-stablizing & throwing the opponent. This stradegy prevents an immediate back cut on you.
The cut/combination can be lethal or non-lethal depending on the target choosen.