Given the general dislike of the final Warpriest design (as compared to the Playtest, where it was one of the most-liked), I figured an Archetype could fix this issue. It works by trading some of the Warpriest's weapon versatility for increased accuracy on Attacks and Combat Maneuvers.
DEVOUT WARRIOR
Devout Warriors act as the will of their deities incarnate, and focus all training on perfecting their skill with the favored weapon of their patron deity.
The Devout Warrior has the following Class Features:
Weapon Proficiencies
Instead of Proficiency with all Martial weapons, The Devout Warrior is proficient only with Simple Weapons and his deity's Favored Weapon (or all Favored Weapons if his deity has several). If a deity worshiped by the Devout Warrior has Unarmed Strike as its Favored Weapon, the Devout Warrior gains Improved Unarmed Strike as a Bonus Feat. The Devout Warrior must take Weapon Proficiency feats in order to become Proficient with any other weapons (characters are always proficient with all Unarmed and Natural attacks they possess).
Sacred Weapon
As the Warpriest class feature, except that whenever the Devout Warrior is wielding a Sacred Weapon, he treats his Warpriest level as his Base Attack Bonus for attacks and Combat Maneuvers made with that weapon, stacking with any Base Attack Bonus from other classes or racial Hit Dice (this does not apply when determining Combat Maneuver Defense, however).
I like the no extra damage for weapons, something I found stupid that the Warpriest would get and not a Fighter.
I think you missed the "as the class feature" for Sacred Weapon; it's identical to the Warpriest's Sacred Weapon as-is, but also replaces your typical BAB with a BAB based on your level when using your deity's Favored Weapon to make attacks and Maneuvers.