"Create a dramatic, rain-soaked confrontation between King Kashyapa and his estranged brother Mogallana. Lightning flashes illuminate their ...

This is really good, very atmospheric. You should get even better results turning on the default prompt in "prompt settings" and maybe even adding your own negative highlighting issues you notice using your original prompt. The default negative prompt might be enough on its own to stop things like the phantom hand and merged hilts.

For both positive and negative prompts it can be worth cutting down on non-descriptive words and repeating key concepts in different ways e.g. instead of "two men stand in a field ready to fight with their swords drawn and water running down their blades" try "two men dueling in a field, battlefield, two men swords drawn, sword duel, rain, rainwater on swords, water running down blades, crossed blades, two men swords crossed", the ai doesn't so much read what you've written as turn it into keywords and specific concepts, so long and complicated phrases can result in it ignoring half of what you want if you're not careful

good work