Here’s what RogueLeader and I have got for Sith-3PO’s translation of the dagger:
We whisper to a darkened heart
Unveil the way with secret art
For faithful Sith whose hatred swells
Wayfinder, only this blade tells
I think the first line is a perfect opening line, anyone paying attention would immediatley connect it to the whispers Rey heard in the cave. However maybe it could be “we only whisper to a darkened heart” to really drive that point home.
I also think the inscription should say ‘Wayfinder’ somewhere, it not only makes things simpler to follow, but it also would warrant 3PO’s reaction to finding the blade, he knows for sure “it’s the clue Master Luke was looking for”, a clue to find the Wayfinder. Though now it doesn’t say exactly where it is, it shouldn’t be too cryptic.
Lando specifically says that Ochi “was carrying a clue that could lead to a Wayfinder”, so I think the dagger should be tied to the Wayfinder. As long as it doesn’t mention Endor and there’s no thingy that lines up with the DSII wreckage it could still be seen as an old Sith artifact. Both the dagger and the Wayfinders could be ancient, or at least far older than 30 some years. Lando says only two were made, but doesn’t say when, perhaps they’ve been carried down through Sith generations, wich would tie to the rule of two and the fact Vader had one and Sidious the other.