Notes:

Fire Emblem and IDOLM@STER fan art by amazing-c

Source: Pixiv

All swordmasters and idols listed from left to right
Makoto = Lackhe (Genealogy of Holy War)
Takane = Karla (Blazing Sword)
Hibiki = Fir (Sword of Seals)
Yayoi = Athena (Mystery of the Emblem and Remakes)
Chihaya = Marisa (Sacred Stones)
Miki = Mia (Path of Radiance and Radiant Dawn)
Amami = Malice (Akaneia BS and Mystery of the Emblem)
Yuhiko = Lucia (Path of Radiance and Radiant Dawn)
Ami = Mareeta (Thracia 776)
Mami = Bridget/Eyvel (Thracia 776)
Iori = Say'ri (Awakening)
Azusa = Ayra (Genealogy of Holy War)
Ritsuko = Lyndis (Blazing Sword)