I dreamed that I was a Taoist who could hold a sword, and then I saved a beautiful female ghost with long hair but pale skin.

You said that you dreamed that you could use the imperial sword, which means that this is definitely not your past life, because the imperial sword does not exist.

It can be said that you assembled this dream.

What books or movies about war have you seen recently? Female ghosts are also associated with demons. The idea of a general dream should be similar to what you see. Maybe you have forgotten it, but it exists in the subconscious.