"Does that mean we can purify the murky crystal?"
"Nothing so good, sadly." Chief Dakkon regretfully shook his head. "When we put the murky crystal close to the god crystal, the two began to react, but not in a good way. The murky crystal did indeed begin to lose some of its cloudiness, but some portions of the god crystal started to become murky! We had to separate the two crystals immediately before this reaction ruined our god crystal!"
In other words, it was like mixing hot water with cold water. If you mixed them together, what resulted was two portions of lukewarm water.
If the Flagrant Swordmaidens wanted to create hot water, then ending up with more water that was significantly colder would be taking a step backwards.
They didn't want the water to grow cold! They wanted to heat all of the water up so that they would all be uniformly hot!