So this probably isn't that important, but I thought it may be fun. The refresher units are fun units to use and they can contribute a lot strategy-wise.
So, is there a special type of refresher you would like to see? Should they be able to attack OR would you rather have them gain other abilities, such as rallying or being able to refresh more units as they level up?
Also story-wise, how do you think they should be implemented into the world? Personally, I think a dancer that uses her talent as a distraction or a cover for an organized military group, or uses it to gain information about enemies could be interesting. A dancer that has a 'mature' feel like Tethys or Leylia/Laylea could be a nice addition to a cast roster, since those 2 characters are well received by fans. Maybe not the most popular, but there's not many complaints character-wise for them.