Wow, its been a while since I posted in any of these User Projects. Well, here's my two US pennies.
I'm confused why we are taking Heavy Armor on skeletons in the first place. From my interpretation, Lahmian armies are designed to closely resemble Tomb Kings ones, and Nehekharan armies went into battle almost stark naked. For this reason alone, I don't see why skeletons should have the option to take Heavy Armor at all, and I don't understand the Full Plate option on Grave Guard either. The more elite skeleton troops seems like a more Blood Dragon theme to me. If you want to increase the effectiveness of skeletal soldiers in Lahmian lists, which I understand entirely, why not continue with the Nehekharan theme and allow them to take more Tomb Kings options such as skeleton archers at least and possibly chariots.
The Swain rule in the older edition Army Book was fine as it was, representing a Lahmian's mortal lover (I'm having fun imagining Saurus Scar-Veterans and Ogre Bruisers...) or mind-slave, but I think the option to take a swain retinue is stretching it. If a Brettonina Paladin fell for a Lahmian, there's no reason why is whole following of Knights of the Realm would follow him. It also, as has been mentioned earlier, opens the door for some very broken combos. Ogres and Brettonians came to mind first (I'm kind of surprised that people caught that as late as they did), but those were easily rectified. Other armies such as Lizardmen - 20 Skink Skirmishers greatly increases an army's offensive ranged potential, not a good thing in an army that you want to be based more on elite combat infantry and 20 Saurus could fill a very solid, not to mention unfluffy core while 20 Dryads or Glade Guard could do the exact same thing. I think that the Hero Swain rule works, but taking units is pushing it.
Anyway, my thoughts.