If you're fighting Mateus now, I doubt you have Embroidered Tippets, I know I don't and I'm just after that trying to beat Cuculaninn with my lvl 40 ish party. Easiest way to level I would suggest is going back to the Henne mines to the second switch where you get ambushed by about 16 flans, set everyone to fira (or one person to fira and the others to steal if you wish) with some basic healing, and set off the trap.

After dealing with them, flee two areas away, and run back, still fleeing, and set off the trap again. The fleeing maintains the chain by not engaging the steelings and other foes, which, while doing nothing for the exp gain, raises the quality of the loot, when you get 99 yellow liquids, just teleport somewhere you can sell them. Massive amounts of exp and gil. Should easily get you to lvl 35, if not more depending how patient you are.

As for mateus, I think I just hacked her to death with a level 35ish party. I might've quickened her too, but I think I probably just hacked, so I can't offer much of a strategy.