Vilna Gaon (from Yerushalmi Brachos 4:2): The honor of Tzadikim rises gradually, until it is very great - "v'Orach Tzadikim ch'Or Nogah" (Mishlei 4:18). Just like light increases until midday, so Tzadikim ¹ .

Malbim: Some Sarim conduct Beis ha'Melech, some conduct the Medinah, and some fight external enemies and conquer Medinos. If [the last] succeed, they are elevated as long as they are valiant and conquer more lands. Mordechai had all three of these appointments. He was Gadol b'Veis ha'Melech, v'Sham'o Holech b'Chol ha'Medinos, for he was second to the king to conduct the Medinos, and he was Holech v'Gadol, for he made many Medinos submissive to Achashverosh, like we will explain (refer to 10:1:1:2).