The dire flail option of the rod of flailing effectively grants you Two-Weapon Fighting when using the weapon. However, it does not grant you the equivelent of Exotic Weapon Proficiency (dire flail). Since Exotic Weapon Proficiency (dire flail) isn't on anyone's list of useful feats, it's hard to see a real market for this item. Was this an oversight, or is the rod of flailing just a really expensive magic item with very limited usefulness?
Morrow
Morrow