Hello,
I do not think it would be a good idea to give back that power to kata, she's already extremely strong at higer level of plays.
The reason behind that is simply that when she was reworked, Riot decided to add some pattern to her kit (place a dagger on the ground, then active it) which is meant to be her main source of damages, while her ultimate is her finishing move and has the counterplay of having the stand there for 2.5s.
Surely you won't get your full ultimate off, however this is intended I believe. The way kata is meant to be played is that you have to set up some daggers, trigger them and then only ult to finish off a target.
I checked your profile and match history, and I can say this much :
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You are SilverV, I am sure that you understand that Katarina is now a champion with a high skill cap which is hard to reliably achieve, and that at you silverV level, it is possible that you may not be using her as, say, a diamond kata main would.
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You are not building the current best items on her. Here are you last ranked matches with kata : http://image.prntscr.com/image/44002759bc0448319851c456546ff4b9.png
Aside from the fact that you went toxic feeding mode and bought mobi-boots only, you are not building a gunblade in any of your matches, even though it's one of katarina's current best items.
You may not have realised yet, but her scalings changed when she was reworked, with her dagger passive having AD and ap scalings, and the rest having lower ap scaling. Also getting liandry among your first items is a really inefficient purchase.
All in all, I think your knowledge and understanding of the game is that problem for this one. I suggest you watch some high-elo streamers who play kata and take advice from them as they commentate their games. If you want some insight, here is a video from Scarra https://youtu.be/kasXuKBCrP0?t=129