A disclaimer: this is all being said as a guy who mains Rath, at level 15, with almost 1400 kills and under 400 deaths. (Not trying to toot my own horn, just showing that I know what I’m doing).
I’ll get to the point: Dreadwind is too powerful. It’s too easy to hit and doesn’t really require any amount of skillful precision. No reduction in damage or speed will really change that. It’s a giant, movable AoE.
Have Rath’s ultimate be something where we get to use Precept (the ultra greatsword on your back). Have it function similarly to Catalytic Smash (where you pull it out and have to activate it again) and give us like 3-5 charged (but slower swinging attacks compared to his basic attacks) swings that we at least have to aim to hit.
Would be much more skillful in my opinion, and also would let us use Precept a bit more. Would also tone down how strong Rath is at end game. Seems kind of lame that the coolest sword we have is little more than a decoration that is only used for a brief second when using Catalytic Smash.