Zed 1 shot me. when I had over 4k hp and and 267 armor

I got 1 shot as Darius by a Zed. but i was full tank Darius with over 4,000 health and 260+ armor. I dont feel and assassin should be able to 1 shot a full tank. he got 1 combo and done he even missed the double shuriken after ult. I have it recorded and will post it when i can get the recording onto and mp4 format. I feel it ruins the game making a champ that can one shot anyone. yes i know Zohnyas ans QSS but tanks dont typically build them, and there is no counter play to the ult outside of those 2 items. Is there something i could have done to live or is it just blatant op nothing you can do? He did this to me every time i was up he would hunt me down combo adn dead i spent more time dead than alive because he would jump into base to get me. (cant damage him while ulting so not much you can do ) we were both full build.

oh i forgot to mention he did also have that dusk blade item which is a zed ult off of auto attacks so he basically got 2 ults not sure if that should make the difference though. i mean 4k+ hp and over 260 armor. with 1 combo missing all shurikens