You can trade an action for a maneuver, but you're still bound by the rules for maneuvers. That is, (1) you are still limited to two maneuvers during your turn, and (b) a second maneuver costs 2 Strain to make.
There doesn't really seem to be a benefit to trading an action for a maneuver. Is the gained maneuver supposed to be a free maneuver?
Am I missing something?