Currently the Nano Saber has an attack speed of 1, which is the same as axes and other tools. But swords, which the saber is one of, have an attack speed of 1.6 usually. This doesn't seem like a large difference, but after playing with the Nano Saber for a fair amount of time as it is right now, I can say it certainly is. That along with the lack of the "swing" than most swords have and the inability to enchant it makes the Nano Saber honestly pretty bad compared to a vanilla enchanted diamond sword.
