I've been seriously working on ki/kokyu skills for approximately two years. What I mean by "seriously" is that I've received specific instructions on training exercises from several high level people. And have been following their recommendations and instruction.
1. One of the most important trainings I've been doing is what is called spear/pole shaking.
2. I just went to Japan, and spent several practices with the Toda-ha Buko-ryu dojo. I've been away 20 years, we have a new soke and the Tokyo dojo has it's own shihan.
3. We have a number of moves in which one deflects/attacks the enemy by "knocking down/knocking up" their weapon. Rather than striking from some separation - the customary way - I was able repeatedly have our two weapons touching and without any wind-up, pull-back or discernible movement, pulse/fling their weapon aside and continue in to a cut that they could not stop.
4. There is always the "danger" of accommodation, due to following the kata pattern - but my training partner, the other shihan, a very big guy, who is also proud of his involvement in another koryu, said that he doubted I could do that if he had a bokken. We tried, our weapon's touching. He locked down his muscles - yet I "flung" his weapon up into his face and cut him in the same motion. He tried again with the naginata, and it was just as easy.
6. Then, for fun, I tried something I'd never tried, but having seen Kuroda Tetsuzan do something similar in a video, I wanted to see what would happen. Linking naginata with one student, I did downward pulse/drops and upward pulse/like flinging snow. I whispered to people off to the side ("neck" and do the move and his neck would come forward, "hara" and do the move and he'd collapse at the waist.). (This is an aspect that is referred to as "jin"). The guy I was working with could not hear what I said, so it was not "suggestion"
A couple of points:
a. These people were not colluding - they were, in fact, defending what our previous sensei had taught them, because I was showing something different and they wanted proof that what I was doing worked.
b. As I said at the beginning, I could show/explain this easily - I'm not even going to begin try to explain here - other than to say it included a ki/kokyu connected body, use of the hara as director of the force, and "ground path" (TM). Seriously, if I meet with anyone reading this, I'll be happy to show what little I know - because I'm still scratching at the surface. I'm not holding back. It does not change the form. It does not require me to assume a special posture, or architect a specific "ki-trick" exercise. It's like shifting from a gas guzzling "muscle car" to a Tesla.
c. the best part of this. Our new soke is young - 40 years old, and very much junior to me and the other shihan in the Tokyo dojo. He stopped me and my training partner and said, "Nitta sensei did not teach it that way." I said, "I know. She didn't teach me that way either. This is something I've been working on. I saw the possibilities in the kata and this is what I've come up with." He said, "Well, I don't know if they used to do things this way in the old days, or if you've found this. But it's far better than what we are doing." And he stopped the class, told everyone to gather around and asked me to demonstrate it, one by one, on each member of the dojo, and then asked if I would show the exercises I used to develop the ability I had. <That is a man worth following - he cares about getting stronger, not about his "position">
As for explanations, I've nothing to contribute that is new, as everything I've learned has come from the "usual suspects."
Having worked with Mike Sigman, Dan Harden, Akuwawa and several high level teachers of Chinese internal training, I know what I know and what I don't. I started out as a 1 on the 10 scale. I give myself a 2.3, at best. These people are far above me - at least so far
I still have a long way to go. But given that the question is if this has any relevance to weapons training, yes, beyond a doubt. It is not at all about being immovable, withstanding blows. The idea that aiki cannot help you because one cannot withstand a sword blow is utterly off the mark of how aiki or ki/kokyu can help your weapon's work.