What use are astrolabes?

I just finished my second shaped region, and the rewards were two pieces of junk jewelry. What use is it to farm a hundred bosses for a couple a astrolabes, only to get trash for a reward after fighting 6 or 7 more double-possessed bosses I could barely fight? I mean, even the shaped maps aren't dropping better loot. So, enlighten me, WHAT'S THIS FOR?

each quadrant has a different possible set of loot from the vaults

the real value of the astrolabes is the map juice(templar for generic map juicing, mechanic ones to juice the mechanic), the non generic one provides bonuses to specific league mechanics.

also you can make ghosts a non danger in the atlas tree, there is a keystone pretty close to the top left to make it so ghosts possess you instead of monsters.