Handling the katana . The usual weapons studied in jitsu clubs are knives, coshes and broken bottles. The value of these are obvious. In fact, sword work is quite practical. Swinging a sword around magnifies problems with balance and posture.
Many techniques are good to practise with swords because they originated in sword work.
Partner work increases your awareness of distance and timing. The kata can be practiced alone in a small space. It is also an unfortunate fact that real sword attacks are happening more frequently. There are also less tangible benefits. The sword is a link to the history of Jitsu, a beautiful objct to use and the ultimate symbol of the samurai.