"Exert once to wound once" would be actually mightier most of the times (an exception would be against
Wormtongue, and other maneuver-skilled minions you need to disable asap). But you're right, I think it needs some other cost to remove the faceroll aspect.
"Exert bearer twice
and discard 3 cards from your hand to wound a roaming minion twice" would accomplish that. Or "and discard 2
cards from your hand."
Madril DoO's OP combos would be nerfed for good if his skill triggered at the END of maneuver instead. Roaming effects would still work during Skirmish and Archery (
ATitA), but
What Are They and
Ithilien Blade would need much more fortification /
Gondorian Merchant labour to work after their natural course.