I would say maybe even to purple, due the extremely specific wording on it (concerning to what it applies to) I think it is highly situational. I mean it could do well in a game that is mostly populated by humanoid, weapon wielding enemies; but in "normal" play it is increasingly difficult to see those kinds of enemies at level 13 (when you first gain access to the manoeuvre)and up .

But my comment is solely based on theoretical play, I haven't played in a game that reached those levels with a martial adept (my DM loves to stop about level 10)