From my personal perspective, perhaps as a katana user..
Paul!
Long weapons have always been overpowered in battle situations, because they never had to pay the logical price, which is speed. GS and Long heavy polearms should be slow as fuck compared to shorter 2h and pole.
1st of all it looks unnatural and breaks a common physics to swing something that huge that fast, secondly, it takes away viability from shorter weapons and
reduces variety. There's simply no point in taking anything else than a huge axe or 2h.
If you want to swing fast you can either go short and heavy, or long, light and stabby. But whatever.. That stuff ain't gonna change at this point anyway. In other words, nerf everything else, buff katana.