That looks exceptional. I couldn’t see how well it handles extremities (arms all the way out) and rapid movement, but the motion looks very smooth. Well enough for any level of immersion I’d expect!
Wouldn’t happen to be willing to share some of your IK solution, would you? I know there are easily dozens of developers on this board alone who would be ravenous to take a look at any good full body examples. Of course, if it’s close to your chest, I understand. 
Edit: I rewatched it, and saw the full extension during your little cabbage patch. Very nice. I also caught that motion of your elbow when your wrist was pointing down on the weapon, then you rotated it roughly parallel to the floor and your elbow did a natural-looking transition. Elbow movement like that is always what I look for when seeing these IK solutions, because I know none of that comes baked in when using out-of-the-box FABRIK/CCDIK nodes.