well we are playing CT not CS and there is no such slash, or at least it is not in the move's list. he can use his distortion-drive counter to counter swords, but i can easily dodge it. Zantetsu uses too much magatama to be a good counter, same goes for kicks.
Nu is not broken - she requires extreme amount of concentration - one mistake in swords or anything and you can say goodbye to 4/5 of her hp. Bursting is deadly for her - after burst she has even lower defence.