At the risk of being jumped on, here is the other side of the story. I took up Shinkendo and practised fairly seriously for 7 years. i have much respect for Obata kaiso's art, and whatever peoples opinions of koryu vs. gendai he is IMHO a master swordsman. Howver I came to a point where i felt it did not add to an overall flow and blend which i was personally seeking in my aikido. The attitude of enter and cut is something I now try to study and implement under the guidance of Hiroshi Kato sensei. His swordwork is Aikiken and yet it sometimes gives me a more realistic sense of flowing with the sword as a part of my body and an extension of my irimi, rather than using a weapon. I believe the idea of "sword. body and ki as one" is the essence of the study.
Most Aikido practitioners who do weapons, especially sword, cannot adequately tell you how what they do directly ties into their empty hand. To my mind, if it's aiki sword or aiki jo, then the principles at work are identical to those at work in the empty hand. One should delineate what those are. If not, then probably what is going on is a bunch of "stick whapping" and really has no relation to the empty hand.
At a seminar I taught once, I was breaking down a set of Saotome Sensei's forms at a level of detail that the attendees were clearly not used to. One stated that he wasn't doing sword to actually be a swordsman, he just wanted to make his empty hand better. I challenged him to tell me how doing bad sword could possibly make his empty hand better.