Thank you for explaining in detail the gist of arguments on the matter.
The Zweihänder / Montante school is very familiar to me, as i have trained with the weapon the most and got a friend acting as montante coach.
First of all (and i will upset some people), all written books on techniques are lacking a minor or major chunk of knowledge from around the world = people who train in HEMA or fencing learn only a % of what is possible with the weapon, but sometimes tend to think they mastered it. So if you see videos of people showcasting techniques, they will likely be limited and should not be taken as "best advise" when adapting any form of combat art.
Edit: To put things in perspective: While i did train with weapons half of my life, i respect any controversial opinion on the matter and do not wish to offend HEMA or fencing schools in general.
Concerning the Zweihänder, the rotational swings are for getting momentum and creating feint attacks to land a hit. If you attack into the rotation, you will likely break his wrist&block. That is why round swings are basically weak movements which allow for a counter, if you see through them.
But lets keep it at that. If the attack is meant to serve the purpose of visualizing a game mechanic, than i would highly recommend animating it in the most realistic way, to not look out of touch with actual combat.
For that, the character has to first initiate the round swing and keep the head on target, then turn head and body into the last part of the swing (when the stretch is as max and forces the body to move with the swing) to complete the attack.
The more agile and fast the attacker is, the less time is wasted on not seeing the target. To make it easier to understand, imagine an uppercut movement as 360° attack, where the blade strikes form feet to head in a wide arc.
You could also try out realistic combos to justify longer swing times, by adding pummel strikes, blunt blade strikes, kicks, shoulder rams, power strikes on a certain area to numb muscle contraction to allow for a longer second comeback hit, which cannot be blocked and so on