Purity and Back in the Bottle are both respectively terrible sequels to The Debt. Ming Tien was a good character for its use, and it really was not needed to see him again.
These two episodes have no plot twists, turns, or suspense whatsoever. There's no real change in perspective of anything: Black Powder is in wrong hands, must get Black Powder and destroy it, twas the premise and nothing else. I also did not like the idea of Lao Ma having two other children (other than Ming Tien), who we're twin daughters. For one, it's not interesting, so why bother, and two, her story is complex as it is - there is nothing more to be added. Both daughter's themselves, one evil and one good, we're just as bland as the idea. Although the actress did a fine job playing both characters (had I not known better, I would of thought it was two different actors), but her talent was wasted with this one.
The only real shinning moments of these two episodes we're the humorous parts with Joxer (and occasionally Xena), which is a sign that an episode is lacking in the overall plot. The comic relief is supposed to be a bonus to an episode, not the best part.