User blog comment:Crimson Storm Mich/Future Units Preview v2/@comment-27960787-20170316142929/@comment-28149328-20170317031255

The reason they didn't give Rhoa or Libera an upgrade is because of their story reasons. The plan was that only Griff and Iris would get upgrades due to the side novel which explores more about them. The others were fated to die in Ishgria thus ending any possible lore expansion for them.