Dream assaults are always hand to hand actions for me and I move like I am under water having little to no impact on my foe. I will invariably wake up flushed with adrenalin, but no weapons ever come into play. As for your dream scenario, a fleeing attacker that has wounded you is a continuing threat to you and others. If you know them, you may have a very good idea of exactly what kind of threat they would continue to be. Depending on my perception of whether they would come back to finish the job or had just flipped out and were intent on stabbing everyone they encountered, I might shoot them as they fled.