With the introduction of Reina, Mashima gets a bit closer to what he may be most notable for in his later works: hips and tits. And pretty lewd armpits, too, if you're into that sort of thing.
Anyway, Haru gains the power of the Rave of Wisdom and the ability to use Silfarion, the Sonic Sword, which allows Haru to move very fast. The sword itself is apparently somewhat weak, but makes up in its speed, but I'm not sure what exactly this is supposed to mean when Explosion is incapable of actually cutting and instead focuses on its magic explosions, so there isn't exactly a standard set for normal sword attacks for the Ten Commandments (or "Ten Powers," as TokyoPop has been calling it).
Much of this volume focuses on the battle with Shuda, who apparently knew Gale Glory in the past. Shuda's Dark Bring, Ballettänzer Zeffrea, allows him to generate explosions in any space to which he knows the coordinates (it's assumed he can easily calculate the coordinates of any location, but I don't think it's necessarily stated that the DB gives him the ability in addition to its explosive power). What's somewhat odd is... you'd think Shuda's explosion power would be pit against Haru's Explosion sword for an explode-off, but instead he just keeps sniping Haru as the Rave Master tries to rush toward Shuda to hit him directly. It actually takes quite some time before Haru decides to use Silfarion again, by the way. Not sure what's up with that.
After Shuda's defeat, he has a change of heart, and develops a respect for Haru not unlike his respect for Gale. But his defeat also angers King, leader of Demon Card, who tries to send another member of "Oracion Six" after Haru. After some arguing, it is decided Sieg Hart must take the job (whom we've seen previously as the Elemental Master who struck Elie with lightning in the recent past), so he sets out to the city of Experiment in pursuit of the heroes... but really just in pursuit of "Woman 3173" ("ELIE" upside-down!). Reina, with her tits and pits and hips, is sent alongside Sieg to make sure he does the job. Haru, Elie, and Musica visit the Symphonia Museum to kill time in their peaceful respite between battles, during which time Elie wanders off and sees a painting that appears to be of her but is named "Resha Valentine," meanwhile a random fortuneteller gives Haru foreboding news of the woman he travels with being endangered by his association, and Sieg tells Reina about Elie's magic power, Etherion, capable of disrupting Time.
One of Shuda's goons is revealed to be a cyborg, and I just noticed he has a Cloud Strife spike in his hair. Shuda operates an airship. More Final Fantasy vibes. Smaller aircraft resemble jets, which is a bit different, and helps to expand the manga's lore toward a more "unique" direction.