After play it for a long time, I finished first part of Aruttio, Daizy, Emilio, and Maria Sharte Partner Story mission. Next part is additional feature added in Boost + version that you can get after you Frontier level is 10+

Here is my partner stat after i finished their first part Partner Story mission.

Aruttio - 2 Handed Sword
Daizy - Light Strike (Mace)
Emilio - 1 Handed Sword
Maria Sharte - Spear

Valkyria Chronicles II is sequel from Valkyrie Chronicles released in 2010, 2 years after PS3 release of Valkyria Chronicle. Windows release for Valkyria Chronicle itself was released in 2014.