Let me make one thing clear
Kalista is heavily countered by attack speed reduction
This does NOT excuse her for being so annoying to play against
That is all. Keep this in mind next time you want to say she has no weakness. The problem you are experiencing is not that she has no weakness - because she does - it's because playing against her is like playing QWOP with your toes.
It's a shame that such a new champion cannot be fully healthy for the game without being completely reworked.