Zed will still be forced to get ghostblade and BotRK first unless he's miles ahead before he can even think about that item. Have you seen it's build path? You get a Dirk, a BF Sword, and some gold. Say you go back with 1150 gold, you get the dirk. Cool, now you need 1300 more to get the next part of the item. It's build path is absolute trash, and you're not going to be able to get it early on. Also the debuff can most likely be qss'ed, so that's a double whammy for Zed. Zhonyas also still exists for a double whammy as soon as he hits you.
Why are you even mentioning Talon? Whoever he goes on is going to almost 100% die in half a second anyways. If Talon has enough gold to buy this item, he could have bought something else and still 100-0'ed you, but since he has the new item and not a Black Cleaver it's time to nerf Talon, right? Even though you would have died regardless if he was fed enough to have the new item over another one?
Last Whisper is almost always a trash item now since it's so situational as well. They won't be killing many tanks with this. It helps against the squishy champs mainly, the ones they are supposed to kill.
I think people are forgetting that if someone has this item, the next person they hit is someone they need to all in because if they don't, they just wasted the passive for 60 seconds.
Example: I buy the item on Zed. I auto someone to poke them as they walk by, because that is a bad place to all in someone at the time. The passive is now gone for 60 seconds. It is an all or nothing item. If you accidentally hit someone else before your main target, then that also is going to make the passive useless unless you can kill them both.
That doesn't mean the item isn't good, but that's something to think about. It's not up 24/7, and relies on you actually being snowballed and farmed so you can kill people to keep it off cooldown.