Lineage from Daito ryu and technical curriculum are both totally culturally contextual!
"Physics" is either universal, or also culturally contextual.
Yes. The "daito" sword - which is the longer katana - is certainly uniquely Japanese. Daito Ryu and Aikido movements as not just based on universal swordmanship, but specifically the katana, and more specifically the daito katana. Daito Ryu....sorta adds up...
Is it still Aikido if you take away the Japanese Daito Katana?
Evidently, the daito katana can and has been, in some cases - even with Ueshiba - replaced with a bokken. And more specifically, the daito bokken.
Another question: Is it still aikido if you take away the daito - whether katana or bokken - as the initial framework for aikido techniques. In my opinion, and certainly the opinion of Nishio and others, no. If there is not an understanding and execution of movements that are based on the daito sword, then, no, it's not aikido.