Not sure if this is an issue or intended, but Stumbling Feint is borderline unusable in the Martial Artist Archetype because it requires Flurry of Blows, which requires either being a Monk (which gets it anyway, albeit at a later level) or taking the Monk Archetype (which prevents low-str/high-dex martial artists like Rogues (who would benefit from the free feint most) from taking it).