As for crucifixes, I've only come across the one now (after defeating the boss I've talked about).
Well, one crucifix is enough (even though there are more than one in the game). Just equip it on your fastest character, and give that char the Heal All-stellar and party affecting status effects should be a little easier to handle in the future. Or yeah, as Dizzy says, equip it on Ricardo and then use the Serenade that protects you from Status and Ring Abnormalities.