I was figuring something similar.
Drop knights with an ancient as the warlord, with the 5+++ banner and master of maneuver. The knights can only be wounded on a 4+ due to transhuman physiology, and get another -1 to be wounded through fortress of shields.
They can only be hit on 6+, can only be wounded on 5+, and have a 2+/3++/5+++ save. Can charge with rerrolls, and hit 41 times for a 10 man squad.
And it costs you only 3cp.
That "cannot be wounded on better than 5+" combo only works in Combat unfortunately but otherwise i agree
Oh, I do believe you are right... Sorry