User blog comment:FairyRaven/Fairy Tail Chapter 397: Steel, Review and Commentary/@comment-25111584-20140826105558/@comment-25335500-20140826115414

There is a small chance that the reason why tempesta did not do anything was that he was concentrating on some sort of a magical (curse)barier so that he would not get affected by the water. I know he is a demon but still it is possible that he could be affected by the water.