Nobunoku is supposed to rely on the user's emotions. Since the user Juubito had a weak and unsure will,
the sword would naturally break fairly easily.
I suppose it depends on the user. And the strength of the jutsus is affected by the user, so I don't really understand
how we can compare.
I would say Juubito using it loses decisively while the Sage himself could use it much more effectively and more
destructively if he so desired.