A shame that probably killed the vampire. I was looking forward to his mind collapsing as he struggles to comprehend that the person he's been trying to kill is more qualified to become the next demon lord.
Dual-wielding the hero sword and the demon lord sword would be badass, but I think the humans and monsters alike would have trouble trusting someone with both qualifications. More likely, Rama will just wield the demon lord sword, and the hero sword will accept Rama's friend, and thus we'll have a hero the humans can accept and a demon lord that the monsters can accept, and together they'll be able to negotiate a peace that won't seem too biased toward either side.