I think we're talking about different postures there. The one in seisan where the shokens are separate but facing into each other is one that also works well for me.
As for swords...technically there is no sword in the kata.
Though I do wonder sometimes if the demos from back in the day used the harder "jo" or not, why whatever stick they were using was in the dojo, and what else they did with it.
However, the shoken posture in sanseiryu is one that I think has some curious elements to it.
Mike's description of using the posture as a wedging trap is one that I'm familiar with.
I have been able to make it work pretty well when I've used the posture to wedge and slide off the line and inside to the point that I can seize onto something of their and then step back and use the turn to yank them off their center. However, used in such a way it isn't a "fight ender" unless a wall or some other nice hard object is nearby.
I've also seen using the same wedge posture with a smaller jerk (little swallow/spit fajingy type stuff) to bounce around what I just wedged as a means of stopping whatever they're trying to do next and opening up some soft targets.
On the trapping part...uechi usually goes to shokens that point in wacky directions when seizing is an option. I know of one very senior Uechi-ka who doesn't really think shokens were ever really meant for strong linear strikes...that shokens are mostly for raking, pressing, or as representing seizing.
The bunkai shown for the posture in kanshiwa kata is a curious mix of the two. You barrel in and slam the guard out of the way and follow with a shoken. The other person fires back a linear strike that you then wedge/trap off the line.
I know of several folks who, at this point, give a little tug on the arm they just trapped using only the pressure of the wedge between the two shokens. I'm curious how that little tug got into that bunkai because I've seen it in lots and lots of places...
But in that bunkai there is no turning.
So what is valid to me is turning tight and hard when you've got a couple fistfuls of the other person seems to have a pretty hight probablility for sucess, relying on the pressure of a wedge alone during the turning seems to have lower probability to me...
So Mike - when you've used the open-handed versions to lock - did it seem contrived to you or really as one of those moves that made you think "huh - well that's a totally easy and natural way to break that guy's *joint*"?
I actually like the move quite a bit - but I really see it as a very close in move (my hands on their body) rather than one done further out (my hands on their hands/wrists)
My judo brain likes the idea of an agressive move forward where the lower hand grabs shirt or arm, and the upper hand shoots past the head to grab the collar/hair. Then you're sinking/seizing/turning all at once to yank them out of their shoes...that's not something I could ever pull off against someone much taller...but could see doing pretty well on someone of my size.
Grabbing what you can and yanking with your whole body weight is usually a pretty good way to get someone to stop thinking about hitting you and start worrying about how they're going to stop falling.