As BLM you really aren't hurting yourself in regards to cross class skills. The big one for (other) casters is actually {Swiftcast}, and you already have it. Another nice to have is supposed to be {Quelling Strikes}, which is Archer (ARC) level 34, but I don't have it myself and I haven't had any issues without it. The others like {Virus} level 12 and {Eye for an Eye} level 34 are tank/boss defense cooldowns from Arcanist (ACN), but a few other jobs have access to as well. You can get {Physick} from Arcanist (ACN) at level 4, but that heals for so little it's not worth actually using. Nothing else is worth it outside of {Raging Strikes}, which you have already.