My guess is that this falls under the heavy bag reasoning. Punching only on a heavy bag will make your punch strong but, only punching the heavy bag won't make you a good fighter.
Chopping vs slicing
If I wanted to have a good idea the types of swings when using a blade and how to use it, then I would probably train for cutting competition. At least this way I get a good understanding of effective swinging to achieve the cut. But beyond that there is no fighting technique
If you really want to be good with a sword then I would say always go ninja lol