Board Thread:LOC General Discussion/@comment-5616072-20130806121457/@comment-8122845-20130828112404

The weakness isn't a stat boost/drop - it refers to the skills. For instance, Ereshkigal and Heinrich have great drop in forest atk. They would be much more effective against forest than a great drop in all atk, but useless against water or fire. Forest and water have similar skills available.