Which of these two intros is better - Headed Off [Fantasy, 600 Words]

Wall of text incoming. Apologies!

Having trouble deciding what and where I want my story to focus on, and looking to get some opinions.

The main crux of the story revolves around a society that prepares for prophecies in advance. They prepare for the execution of the Dark One too early, and craft the one weapon that can kill him 100 years before he's even born. It gets all rusty in the mean time and shatters when they try to use it, dooming the realm forever, and people blame the executioner.

However, I'm having trouble deciding whether or not that's just some background for an even bigger story. This bigger story would see the Dark One reign terror for years, the king of the realm eventually plunge a magical sword into the ground and create a one-way barrier that divides the world in two and keeps the Dark One (and those trapped on his side) out, then decades later, our story starts with his favorite niece crossing the barrier, forcing him to confront the half of the world he abandoned. This would see more worldbuilding-based stuff, like showing how cultures have adapted over the years to be nomadic to avoid the Dark One, or how structures aren't built to be as permanent, as they know the Dark One will just come and burn them down soon.

That's the story I've spent most of my time building, but now I'm wondering if it's too big and broad. Instead, I'm wondering if perhaps we can follow the executioner in the immediate aftermath of this story. For my two intros, the one with the cloaked men would have the disgraced executioner get a job at his local university in their decapitatorial sciences department, and it'd have lower stakes. Alternatively, the other intro would have our executioner going on a journey after he's banished from the realm to try to find another way to stop (maybe trap?) the Dark One to make up for his folly. Much higher stakes.

Just looking for some general thoughts on all of these plots, I guess, and which seems best. Any and all feedback is appreciated thanks!