Or maybe they're foreshadowing the future... like another episode where you face the Demon King alongside with Iris and save her from the Demon King's curse. After that they could make more content after that fight where you continue to explore the world of LaTale.
And I realized the "Demon Fang" bit sometime after I posted my message when I saw the Sword OH video. Silly me...
"Invoke... VIRUS SOUL!!!" ~ From my VirusChris manga project