Practicing sword work has me thinking about "Aiki", particularly in light of all the internal skill stuff.
I think it's obvious that sword work can (should?) include internal skill. Just look at Kuroda Tetsuzan
(I think that foot-thing they discuss around 1:50 has to involve some kind of internal movement). There's also the idea of "projecting one's ki" into the sword, such that it becomes unmovable. That sort of thing seems inherent/implicit in Ono-ha Itto-ryu.
Much of the discussion of internal skill implies that "internal skill" = "Aiki". This implies that the popular idea of "flowing" & "blending" Aiki is misguided.
But the "connecting" one can do in sword work is highly limited. Sword work definitely seems to include alot of "flowing & blending" (in that video of Kuroda, they call it "moving through the gaps and spaces in [your opponent's] mind"). Though to be fair, I think the idea of "flowing & blending" you get from sword work is slightly different from what you get in popular Aikido.
And here we must acknowledge that Takeda Sokaku was known as a swordsman before he started teaching jujutsu. Thus it seems likely that he would practice this type of "flowing & blending" strategy.
OK, so I believe high-level *empty-hand*
Aiki has to involve some measure
of internal skill. But if you believe that Daito-Ryu was based on sword work, or at least incorporated Sokaku's experience as a swordsman, it seems that "Aiki" would also include the "flowing & blending" idea. Daito-ryu kata, the jujutsu portion at least, does seem to involve alot of this.
The question would then be, what ratio of each makes up "Aiki"? Is Aiki primarily internal skill, or is Aiki primarily flowing & blending, with just internal support? I don't know, it's just stuff I've been thinking about.