It has been occurring since the latest patch.
When using the skill "Whirlwind", the skill motion is done with bare hands while the weapon is stored in the back or waist.
Needless to say, similar skill may exist elsewhere.
Needs fixed.
<P.S.>
As an aside, can't you do something about the motion like a large one full turn Rolling Sobat of the female character in "Blasting Cyclone"?
This is something that has been bothering me since the RoM days.
I'd like it to be a proper sword swinging motion.
It's spoiled the fun. Care to try to fix it, PLAYERNET?