If we wanted to make the dagger something ancient, and the description more generic, you could give it an inscription like this:
“To be worthy of the Wayfinder,
the final test for the great Sith secret,
One must wield this blade,
Sacrifice their light,
And embrace the call to the dark.
Only this blade knows, only this blade tells.”
On the Redux thread I mentioned the idea of adding intelligible whispers to the Sith whispering, so when she picks it up in Kylo’s chambers, maybe over the Sith whispering we can also hear a faint whisper of the word(s), “Endor… Death Star…” Perhaps Rey’s eyes could turn faintly yellow just to indicate Rey is tapping into the dark.
If you wanted to just show a flash of the Death Star, you could change the word “knows” to “shows” in the inscription.
And then, when Rey is standing on the cliff edge, and when she traversing through the Death Star wreckage, we hears specific whispers like, “Come”, “Follow”, “Here”, etc. It would be a nice touch if the whispers were coming from specific audio channels depending on the direction the Wayfinder is.