EDIT: Also when I say “ancient” I definitely don’t mean 30 years. Not sure where you got that impression, MR.
The dagger was made to pinpoint the location of the Wayfinder on the DSII which would’ve only been there around 30 years. The movie treats the dagger like it’s ancient but it’s not possible if that was its original purpose?
Who ever said that was its original purpose? Its original purpose was simply a weapon, because, you know, that’s what daggers are used for. Ochi simply modified it with Sith runes because he thought it would be cool for it to point to something only he knew about.