I wish I had a screenshot (actually a video would have been more useful) but healing power, restoration, can get stuck and it can result in an awkward animation...putting it mildly.

If I replicate it i'll try recording something with fraps.

I replicated the bug by generally trying to fall and begin falling while starting the animation for restoration. This can apparently occur with other powers. I'm guessing it has a chance of happening when two animations try to trigger in comparably similar time frames.

Edit: I found falling probably triggers it far less, I think it's the damage frame animation in which the character is lifting his left arm/hand up after recoiling I guess. If certain powers activate during the right frame it'll cause the whacking bug. This can happen during combat, but also somehow damage frames may occur in jumping in the right circumstances somehow, also causing the animation glitch to occur. I suspect it's the damage animation itself causing the glitch somehow, I guess looping through a tiny section, leading to the embarassing glitch.

This bug happened as I was uploading a video of it while I was in combat with a monster that seems to camp the spawning point.

Ask me in discord I'll share with you, I rather not get my youtube account flagged by listing the video in a public forum.

Edit: It can happen at the exact time of taking damage(that causes the animation) if you hit restoration, and possibly other powers. The bug also tends to stop the player from targetting anything else, constantly causing the client to retarget the player character. Attacking mobs will end the animation bug reliably, as will trying to attack other players but it's harder due to the re-targetting associated with the glitch.