I'm hoping that someone could help me with fastening a dao or a jian to a belt or sash. I know that some people just carry the sword in hand and throw the scabbard aside when using the sword, but I've heard that there is a way to fasten the sword to one's hip and still easily remove the empty scabbard. I've looked everywhere to find the answer, and hopefully, someone here could help me.

One traditional method is slung over the back with the hilt up over the shoulder.

Beyond that it depends on what sort of sash is customary in your school. How many times is it wrapped? How wide is it? What sort of furniture does the scabbard have?