He feels a lot like old Rengar in that you either blow your target up instantly (and then die), or you don't and you end up dying anyway. Kha can get out with 6 seconds of invisibility + damage reduction + speed boost and Zed can just pop back out with his ult shadow. So much of Talon's damage is tied to his only escape that you have to choose whether to double-tap it before they can react, or run away with it (although it is only 3 seconds so it isn't really enough to get away).
He is the least safe assassin in the game, but doesn't do a ton of damage to compensate.
I would say remove the silence from his E (Riot is looking to remove silences from all assassins anyway) and add some other functionality to it, such as being able to jump to an ally with it (but maybe increasing the CD if you do that).
Also the damage amp is pretty low for an assassin. 15% isn't much (it has to be level 5 to get to that) and it also only lasts 3 seconds. Ahri's charm damage amp lasts twice as long, and has a 2 second stun attached to it, along with a decent amount of damage. It makes sense that it should be a bit stronger because it is a skillshot, but it is a LOT more powerful that cutthroat and is not punished at all for missing it. Zed gets 25% AD with Living Shadow at level 5, and the jump can go anywhere, not just enemies. He also gets a further multiplier with his ult amping his damage 20/35/50% !!
I realize Talon has higher non-amped damage than Zed, so my suggestion is lowering the damage on all his AoE skills (Rake, Shadow Assault) and increasing the damage amp on Cutthroat.