It doesn't look like she'll be able to revive fallen heroes, but having a priest in my party is going to make Dragon Quest IX much easier.
For starters, the game's churches no longer have a monopoly on revealing the amount of experience characters need to level up. Outside of bringing dead party members back to life, I'm hoping that having a priest with me will allow me to basically start my own religion in game. Based on my current party's jobs, it would have to have a magical minstrel thief at its center.
The grinding's going well, too.
Not only does my party feel more complete with a fourth member, it's also neat to see how quickly a new addition develops. A few battles here, a few bouts there, and already Peridot is just 10 levels behind everyone else. If I can somehow coax more metal medleys to appear in the Bad Cave, that gap will quickly close.
Though, the flip side of bringing a new party member in at this point in the game is that the gap will never entirely disappear.
For the rest of the game (barring any situation where Peridot happens to hang onto life while the others fall and the monsters faced have only one more round in them) my original three characters will be ever so slightly higher levelled than she.
But that's a small price to pay to wrest back the ability to see how much experience a character needs to level up.