What is the explanation of the warning that Abigail pointed to Mercy and Mary in Act 1?If you could please include the word by word meaning of this...

Abigail's threat to Mary and Mercy in Act I is very blunt in its meaning.  If either of them tells the truth about the charade that she is engaged in, pretending to see spirits, identifying witches, she will seek them out in the dark of night and kill them, a pointy reckoning is the knife that Abigail will use to kill Mary and Mercy.

Abigail Williams is a cold, calculating individual who is on a mission to be reunited with John Proctor, her former lover.  She is determined to get rid of his wife, Elizabeth, so her threat to Mary and Mercy is serious and deadly and meant to intimidate them into following her lead and not stepping out of line. To not get any ideas to tell the truth about what really happened in the woods. Abigail doesn't care if innocent people are put to death for witchcraft: her goal is to protect herself from being punished for her actions and in the process get rid of Proctor's wife.