That's actually just a shield bug. I've had it happen when equipping shields. Twice. Your arm kinda bounces when you equip a shield and I assume what we just saw was some infinite loop with the physics. Killed my character on the first occasion. launched them into orbit (the map became a spec) and then died; the second time I saw it happening, and quickly unequipped the shield and reequipped it and it was gone. Wouldn't call it super rare, but it's also not overly common. Hard to reproduce, I've spent about an hour and can't do it reliably. The Devs are spending a lot of time on shields soon, should go away.