Sidequest: The Slums of Dorter

Balthier proposes an alliance with your group, but you're still outnumbered in the fight. Fortunately, the enemies aren't really that complicated. The Monk opponent knows most of his related skills, and can do some damage with Aurablast and Shockwave, but otherwise your normal tactics should work fine in this battle. Balthier is exceptionally strong with high speed and a powerful gun and will likely take out multiple enemies on his own. One of the enemy Archers is also equipped with the Gastrophetes, which is the best crossbow in the game. If you have any thought of using Archers, it's worth attempting to steal it before finishing the battle. No unit is particularly dangerous past the Monk or the Thief (Steal Heart can be a pain), so once you've taken them down, you shouldn't have an issue with the rest.

After the battle, Ramza and Balthier introduce themselves. Ramza warns Balthier not to continue his search for the Cache of Glabados, as it is much too dangerous. Balthier recognizes the danger, and as Ramza knows the path, he insists upon joining the group and insults Ramza in the process. Ramza walks out of the area altogether, but Balthier persists, and you're given the option to recruit him. Do so.