Was the Son of David expected to bring mercy?

Matthew, Mark, and Luke record blind men calling out to Jesus. For example (NET):

27 As Jesus went on from there, two blind men followed him, shouting, “Have mercy on us, Son of David!” (Matthew 9:27 similar 20:29-31 Mark 10:46-48, Luke 18:35-39)

In each case the blind see and call upon Jesus as the Son of David. While they eventually ask for and receive their sight, their immediate request is for mercy.

What is the reason the blind are seeking mercy specifically from the Son of David? Is there a Scriptural basis for looking to the Son of David as bringing mercy?

Was there an astronomical origin of the Star of Bethlehem in Matthew 2?

In Matthew 2:1-12, there are mentions of the Star of Bethlehem, specifically

Matthew 2:2

and asked, “Where is the one who has been born king of the Jews? We saw his star when it rose and have come to worship him.”

Matthew 2:7

Then Herod called the Magi secretly and found out from them the exact time the star had appeared.

Also, is the subject of many Christmas carols, including We Three Kings of Orient Are.

My question is, is there evidence to suggest an astronomical origin of the Star of Bethlehem?

What were the wise men?

Matthew 2 recounts the visit of the wise men to the nativity:

2:1 After Jesus was born in Bethlehem in Judea, in the time of King Herod, wise men 4 from the East came to Jerusalem 2 saying, “Where is the one who is born king of the Jews? For we saw his star when it rose and have come to worship him.”

As they brought three gifts, western tradition numbers them at three (though some Eastern traditions, especially Syriac, count twelve).

The only indication of origin in the text is that they came from the East. Tradition holds they were kings. Matthew calls them μάγοι. This is often translated as “wise men” or transliterated as “magi.” The notes from the NET Bible state, “The Greek term magi here describes a class of wise men and priests who were astrologers (L&N 32.40).” What does it mean that they were “wise men”? Was this an official title in the Eastern realms or more of an honorific? What more has been learned of such “priests and astrologers”?