Just nerf str builds and polestun can stay. Basically everything that seems imbalanced has something to do with str being op and agi being not so good choice.
Also, why there is 50% chance for polestun to happen? Isn't that a bit too high of a chance? Imho every special feature (polestun, crushtrough, knockdown) should happen once in five cases (one in four if weapon is triple heirloomed). 20-25% chance is much more reasonable and wouldn't annoy anyone but weapons will be balanced and different.