Originally Posted by
Aegis013
I disagree with your assessment, but in the end it's just opinions.
The baseline Crusader isn't the strongest of the ToB classes (that goes to the Warblade), however, Crusader does have the highest optimization ceiling. If you look into the Idiot Crusader concept, you'll see just how ripe for abuse the Crusader's recovery mechanic really is.
As far as Devoted Spirit being the worst of the unique schools, it's my opinion that it's actually, overall, one of the strongest of the unique schools at its baseline. It provides mundane (Ex) healing while allowing the Crusader to also deal damage, providing one of the most effective combat healing methods in the game. It's biggest asset though are its stances, which are unfortunately easy to put aside seeing Crusader's extremely poorly thought out stance progression. However from the first level to the end, Devoted Spirit stances are typically some of the best in ToB. Martial Study allows unlimited out of combat healing, Iron Guard's Glare actually allows you to give an enemy a reason to attack you, Thicket of Blades is a must-have for melee lock-down, Aura of Chaos when utilized with large dice pool damage (such as sneak attack) can substantially increase average damage, Aura of Perfect Order provides a way to mitigate RNG, something optimizers will tell you is extremely important for creating a very powerful character, and Stance of Immortal Fortitude, which is just really powerful right on the tin.
I also disagree with your assessment of Righteous Strike of Vitality, and I believe it's one of the more powerful 9th level maneuvers. Typically healing in combat is considered a waste of an action unless it's the spell Heal. Heal generally provides enough HP boost/status effect relief that it can be a useful choice over damage. Strike of Righteous Vitality not only lets you cast Heal, it does so as an Ex ability, and lets you damage your opponent simultaneously.
Now, these are my opinions, and they're no more or less valid than yours. But with the Crusader's optimization ceiling being the highest of the bunch, it's hard for me to say it is the weakest.