Dreams about fighting and death can be quite intense and often carry significant emotional weight. If your sister dreamt about you fighting and getting killed, it could symbolize several things:

1. Concern for Your Well-being: Your sister may have underlying worries about your safety or health. The fight could represent her anxiety about challenges you might be facing.
2. Conflict Resolution: The dream might reflect feelings of conflict between you two or within her own life. It could symbolize a struggle she perceives in your relationship or her own internal battles.
3. Change and Transformation: Death in dreams often signifies change or transformation. Your sister may be processing changes in her life or yours, and this dream could represent her feelings about those transitions.
4. Emotional Expression: The dream might also be a manifestation of her emotions. If she has been feeling overwhelmed or stressed, the fight could represent her need to confront or deal with those feelings.

Encourage her to reflect on her feelings and any recent events that may have influenced this dream. Understanding the emotions behind the dream can provide valuable insights for both of you.