(I'm an idiot and misread the prompt, so going to completely change my post. and leave the original at the bottom marked out.)
Allow the harbinger to use the sacrafice ability that all the engineers can do, with the cost of the harbinger it would make it a real strategy when you have large armies of harbs to use half of them to get a gc out quickly.
Give the Aurora a 50HP shield. I know it'll never happen but I love the idea of it the more I think of it. give it the ability to survive t1 bombers and make the faction consistent having every main battle unit feature a personal shield (obsidian and harbs being the other main battle units.)