I'd like PLD to get Banish III, not just because of spell progression which is part of it but they are Undead Killers. I'm kinda sad that's not emphasized more. They have a host of undead-killer JAs and augments to Holy II. I think it would be reasonable for them to get Banish III.

WHM should definitely get Banish IV and Banishga III. Since Banish III already lowers the special defense down to nil amounts, except on hounds where it actually deals more damage than normal with Banish III. Banish IV should do enough so that all weapons get a damage bonus for 60 seconds versus Undead. I think it would be pretty cool. Seems odd that Light Elemental can cast Banish IV already but WHM and/or PLD can't.