I think the Talk Skill abilities other than Invitation tend to be overlooked. But Praise, Threaten, Preach, and Solution are tremendously useful for permenant Faith/Brave raising lowering. Not only for the advatages in physical and spell damage, but making Move-Find and learning Zodiac much easier.

I underestimated the usefulness of Draw Out, since the best swords are rare. Now that I know you can duplicate them (or get them by catching in Deep Dungeon if you want to play fair) I'm going to use them a lot more.

I found another use for Move-MP Up: when Ramza is hitting enemy Summoners with Zodiac, so they can crystalize and get picked up by an ally. He can cast Zodiac once, then walk around and get enough MP to eventually recast without using Ethers.

Agreed on the usefulness on MP Switch, especially with jobs that don't use MP (like Math Skills).