A Question on War

I decided to romance War to get the option to kill kim, but now I'm having doubts. I know if we leave him alive, he will help in the final battle. But is the sword that we receive if we kill him of any real use? I checked the walkthrough and I couldn't find an instance where it was used. Someone pls help me 🙏🏻 Can someone also tell me why this post may have been removed from the main sub? I am new and am not familiar with the rules yet.