Mo Hua chatted a bit more with Cheng Mo, telling him to rest and recover, then returned to the Disciple's Residence, where he secretly took out that severed arm from the monster cultivator.
This arm still carried traces of Monster Qi, which, according to Sect rules, could not be brought inside the Sect.
But Mo Hua had already explained the circumstances to Elder Song, so he had a legitimate "pass" with Elder Song.
Although Elder Song didn't really know what use Mo Hua had for the arm, this thing itself was a "trophy" from their victory over the monster cultivator.
Mo Hua said he had his reasons for keeping it, and Elder Song, after hesitating for a moment, ended up returning it to him.
The monster cultivator's arm still contained some residual Monster Qi, but it was faint and barely there.
Even if Mo Hua had it, it wouldn't cause any real harm.
Besides, Mo Hua was a Disciple valued by Elder Master Xun.
