Yes, mayaBug is right.
In my concept : when object was binded to the skeletons (bones), it's like the object's component was deformed by the bone "ONLY".
The binded object didn't have changed on its WORLD SPACE transformation data, although it was following the bone's movement.
( Move the bone and watching the object's translate XYZ attributes changing in the channel box.)
If u parent other object to a binded object, that means: the object was parented to a surface which didn't move.
(I hope I can explain it clearly

, 請支持.)