Why did he say "bi'Sh'ar Medinos ha'Melech Mah Asu"?
Malbim: Even in Shushan, the capitol, where fear of the kingdom is on them, they had so many enemies that they killed 500. Who knows what happened in other Medinos, where there is less fear of the king. Surely their enemies stood against them even more!
What is the connection of telling her how many people they killed, and asking what else she would like?
Torah Temimah citing Megilah 16b: When he said [Rashi 16b - angrily] how many people they killed, an angel slapped him on his mouth. After this, he asked what else she would like.
Malbim: Since we see how many enemies the Jews have (refer to 9:12:1:1), what do you want to do to save the Jews from the danger hovering over them?
