When a Body Ring is used on a unit, it permanently increases the unit's Constitution by a set number of points. In Fire Emblem: Thracia 776, it boosts Constitution by 3, and by 2 in all subsequent entries in which the Body Ring or Statue Frag appears. In Path of Radiance and Radiant Dawn, which feature an additional Weight stat, the Statue Frag also boosts the target unit's Weight by 2.
The Body Ring's positive effects include improving its user's ability to bear heavier weapons without suffering from Attack Speed penalties, alongside their readiness in Rescuing other units. Conversely, the user's increased Constitution makes the unit harder to rescue.