[Snake]

1- I don't know why remove the refund from the Green Geist Schritt, the Blue one's refund could be removed because a basic hit often nukes better than an autohit or magic, so it makes the Boxer become split between 'Do I go for major battle-disturbing defensive or a full-power counterattack combo?', and the Blue one is already uber battle-disturbing due to the range of things it affects. (Even non-damage skills that try to debuff the opponent, like Absolute Death.)

2- Yes. Boxer is supposed to be a high Physical Damage dealer and period, so having Asura Fist doing Magic Damage makes it a bit 'eh' in my opinion. Such 'Physical Damage mixed with Magic Damage' gimmick would fit better on Monk and Verglas. As one uses spiritual power and their bodies to their maximum and the other uses infused Ice and many kick techniques. Yadda yadda.
Asura Fist's damage type should be changed to Physical and I can guarantee it would solve a lot of this skill's problems due to how easy it is to stack Physical Damage reduction. (Which were Matador's previous problems.) And maybe add a condition to make it reward 2 points of Schwarz Sturm, such as 'if you hit the opponent on the front'.

3- Damage's not a big-ass issue if you have prepared yourself to fight a Boxer by stacking Phys Damage Reduction, atleast after the nerf. Asura Fist is the big offender here in my opinion, thanks to it, they can build Schwarz Sturm too fast and that's not cool.

4- Nachbeben is 'okay' for now, I wonder if Wind Resist makes it eat the Boxer's momentum, but that would be more fine if it was like, 10 magic damage + (2 per rank) + 50% Wind Elem. Attack (+10% per rank), to encourage the Boxer to not just choose rank 1 Nachbeben and do a lot of 'AoE re-damage' for 1 skill point.

5- Nah. It's fine. But if it gets too annoying, we can always make it so Spiked Threads nullify the pull's effect.

6- Magic Gunner can abuse such thing better, so no biggie. (WIL increases their overall damage, plus gives them physical damage reduction.)

7- YES. Make it so that for the duration, using Martial Artist skills will make you lose only 1 Schwarz Sturm (2 for non-offensive skills) instead of a complete reset. If this goes through, I think Boxer could use a big ass nerf to all of their skills. And another playstyle of Boxer could be put on the road here! THIS WOULD BE GREEEEIGHT!!