Would love to see a Rest or Camp command (not unlike Civ Rev), or a healing kit that can be equipped on a unit (so I can create a Healer or Medic unit).
There is a Healing Pack that you can put on your units. It's quite expensive and gives a +1 Health Regen and +5 Health for 25 gold and 2 material per unit. The description is "this pack contains various items used by medical practitioners." I just got to the point where I've put it on a few units, but haven't really had much of a chance to experiment with it. I suspect that's health regen on that specific unit only though in spite of the name and description. I also don't know if this works both in and out of combat.
There's also a Health spell domain which you can unlock if you research far enough up the Magic tech tree. Again, I haven't had much of a chance to experiment with it, but as far as I can tell the Heal spell only works in combat. There's also a Mass Heal which I haven't researched yet.