I feel like the katana kind of stinks to use. The vertical height that you get even while grounded makes it hard to attack other players. I think depending on the direction the player is looking at, it should be where you dash. If you want to dash straight you look straight. if you want to dash upward or downward you should look upward or downward to dash there. I think the katana would be more fun to use if you could dash like that.
I definitely agree that the Katana dash needs some sort of tweaking. It feels really unreliable and like it flings me wherever it wants.