Thanks for the ideas! Mao has an ultimate skill he will unlock as part of a side quest, which is gonna be a high risk high reward move. I'd love to give him a backstab or stealth attack skill that only works if he uses "hide" first (much like some skills in Darkest Dungeon), but I don't think the default RPG Maker lets me do that ;-;
As for spells, Lianna learns her final level up offensive spell at lv 7, and two more utility skills. She will unlock an ultimate spell as part of the main quest soon tho. On top of that, there're also ice and lightning spells she can learn from magic tomes, but for now only a lightning one is hidden in the game, and there's a more or less hidden ice spell tome you will be able to get during chapter VIII (which I plan on releasing next month).
As for being low on coin, feeling broke all the time is mostly intentional lol. But a good way of getting Coppers is handing over your surplus of herbs after you finish a mission, like the other comment said, as well as just exploring well and selling your old gear at any shop. I hope that helps! (^^)/