A shot in the dark, but.... because they're lucky?
Yes, but why are they lucky, in Castlevania terms?
Wait, so that was the question?
Since when did we have "Sagittarians" in Castlevania? The only centaur I can think of is Eligor.
Eh, I wouldn't consider myself "lucky" if I spent my time dropping rare items...
Okay so... I figured that I would phrase my questions in a more "puzzling" manner, since you can simply find every answer on the internet (I refer not specifically to Castlevania, but everything, like "luck Sagittarians"). I though it would be more interesting.
The answer would be anything including the "Lapis Lazuli", since it is a lucky stone for Sagittarians. Like "Because they always have a Lapis Lazuli equipped" for instance. The Lapis Lazuli is a luck stone for the Sagittarians, as
this link and
this one say, and it increases Luck in SotN (and other games too). My bad if it turned to not work xD
Dropping a rare item on Castlevania is affected by Luck rate, so yeah...
Just an addendum, I know the horoscope is pretty much bollocks, and that many places claim differently about the luck stone. All it mattered is that I mentioned one of the signs that included the Lapis Lazuli for it to work out, since it is the only "luck related" item in Castlevania that's also associated with luck on the horoscope.