I may be being dumb by relying on what HeroLab tells me here, but I can’t find an errata to confirm this one.
Can a Sacred Fist, who hasn’t (and can’t, before anyone suggests it) multiclass monk, and has no flurry-related feats use their sacred flurry with any weapon other than unarmed? I’m specifically looking at shuriken, after running into one too many monsters that damage you when you hit them :(.
Flurry of Blows (Ex): At 1st level, a sacred fist can make a flurry of blows attack as a full-attack action. This ability works like the monk ability of the same name, except the sacred fist's attack bonus from warpriest levels does not count as his warpriest level. This ability replaces sacred weapon.
Flurry of Blows (Ex): Starting at 1st level, a monk can make a flurry of blows as a full-attack action. When doing so he may make one additional attack using any combination of unarmed strikes or attacks with a special monk weapon (kama, nunchaku, quarterstaff, sai, shuriken, and siangham) [...]
So you can flurry with unarmed or any weapon with the 'monk' quality. It's best if you're proficient (but not technically required!) but Sacred Fist gets proficiency in most monk weapons, including shuriken, so you're set.
Sacred Fist gets proficiency in most monk weapons
It really doesn't - Sacred Fist is proficient with 6 out of 36 monk weapons, and just about the worst ones. Shuriken is basically the only good one on the list, due to the unusual nature.