A number of years ago, I was watching a tape of Yagi Meitoku sensei doing Seiunchin kata. He must have been in his 80s by the time they filmed this. He looked feeble and sometimes even a bit unsteady on his feet. But he began the kata, stepping out with his right foot into shiko-dachi with his hands simultaneously moving up and out, back-to-back with the palms up, and then closing and pulling down, ending over each thigh. The difference I had noticed was that Yagi sensei did not step out to a right shiko-dachi with both open hands pointed down. Nor did he step out to shiko-dachi and then bring the hands up, palms down, fingers pointing towards each other, then separating them, making a circle until the backs of the hands meet again out in front of the chest...as at least one noted teacher does who heads a large "international" association.
I have seen various interpretations (or bunkai) for each of these movements. In the first, people have suggested that the defender is responding to a bear hug from the rear. In the second, the defender is supposed to be responding to a double lapel grab or a two-handed choke. The problem with the first idea is that there is no follow-up shown--that is, the techniques that follow the first move don't have anything to do with someone attacking from the rear. The problem with the second idea is that it ignores the feet, stance, and direction of movement--not to mention some of the principles of Okinawan karate. Why would you step into an attack of this nature?
But I just think--and I mean no disrespect by this, in fact, quite the opposite--I just think maybe the old guys may have known something that didn't quite get passed on to everyone. When Yagi sensei steps to the right into shiko-dachi, he is stepping to the outside of the attacker, who has grabbed the defender's left wrist with his left hand, or he is punching with a left punch. Yagi sensei is stepping in, but off line, to the outside of the attack. His arms move up at the same time as he steps in. As the arms are brought down and the hands close, the left hand turns over to grab the attacker's wrist, and the right arm comes down on the attacker's elbow. This brings the attacker's head down. The defender's right hand then grabs the attacker's head, while the defender's left hand comes in to attack the opponent's chin or throat. This is serious self-defense. It shows off-line movement. It doesn't allow the attacker multiple attacks. And it's far more deadly. Just like Funakoshi sensei and the cat stance, I think Yagi sensei knew exactly what he was doing.