I never said Vi was a tank, I said buying tanky HP AD items, and out damaging everyone when others have to buy raw AD stats to do even a fraction of her damage. It is not fair that someone with 3.5k hp and around 200-300 AD can out damage someone with 1.8k HP and around 500 AD, crit, and Armor pen, just because "they were designed for it". They put 0 effort to get the damage, while others dump all their gold into it.
As for the Talon issue, he is by no means, in a good state right now. As a talon (and riven) 1 trick I can promise you that. Even my friend with 1 mil mastery on Talon dislikes it. They made his roaming stronger, yes. But they failed to give him a way to actually get on someone after the Roam. Take Sol for example. His entire kit is to be a roaming mage. He shoves in lane, roams bot with his E and Q, and gets a mass lane stun, with the range and sticking potential to make it work. Talon? he hops a wall and... walks at you slowly because they made his base movement speed lower..? Yea..thatll sure get the job done.. Talon has good damage, and it allows counterplay, but he has no way of getting to anyone without them being right next to a wall he hasnt marked. His 3 hit passive is also awful. It's damage is nice, yea. But its as if Riot did not even think of how he would proc it. Vayne? 3 autos or 2 autos and a condemn. Gnar? 3 Autos or a boomerang. Ekko? Anything in his kit except his stun, and autos. Talon? Rake and Q. Ya know.. the move that has 2 seconds to walk sideways and avoid..? And the Q which is either his low damage approach, or hard hitting crit if hes somehow in your face all ready. Yea, his ult can too..but unless you're annie and flash ulting, you will never get the initial damage of the ulti out on someone, so only the blades converging will apply the stack, which is also about 2 seconds for the enemy to move, and all of Talons damage was DUMPED into his 3 hit passive, which he can almost never even apply to someone.
Now, as for Duskblade of Draakathar.. Yea you are right, it can be used by anyone in theory. So could mana potions. Those got removed though for, in Riots words "Massively making some champions unfair, while having next to no impact on other mana users". Duskblade can be used on Talon, Zed, hell even leblanc, but it can't be used gold effectively. Kha goes invisible everytime he enters brush (on a relatively short CD) plus his ACTUAL ult. In a skirmish, Kha can go invis 5 to 6 times, meaning 5 to 6 Duskblade procs. Rengar's entire kit relies on bushes or ulting with invis, so if the player is using him correctly, he can get just as many procs as Kha (assuming they arent dead) But as for Talon and Zed.. they are meant to start from a brush (or invis in talons case) and run into a lane. On average, you will get a single proc for an assassination..and while the stats on them may be good, Id be better off getting the Defensive item (i honestly forgot the name) which gives slightly less AD, a spell shield, and then the same lethality and movement speed stats, which on Talon and Zed, is NOT something you want, because your kit encourages you to go in, and kill your way out or die. Less AD for a spellshield hurts those two more than anything, but it's the only "Viable" item to replace duskblade.