Leveling Retainers and Other Retainer QoL

[TaleraRistain]

I think the main problem with sharing experience would be that technically the retainers dont exist until summoned.

however, if once we have capped, might be nice to be able to bank exp for them to apply to them when we do call them out.

Or maybe when you go out, they can tag along with you. Banking exp also isn't a bad idea.