Honestly it depends what smite upgrade you take whether you would go damage or not... If you're going with smite a player trinkets then you would get damage... and if you're going with smite reduced by half when it kills a big minion and running util masteries for like 15 second smite cd's and trying to scale you're probably going to wanna go something like
0/21/9 masteries with attack speed runes for your w obviously and the reduce smite by half when it kills a big minion thing and you're going to wanna get the tanky thing and just spam farm and gank when your ult is up.. and then late game the % damage on w and Vi's retarded scaling will give you all the damage you need..
I probably wouldn't run damage on vi just simply because it's like running damage on WW why be a glass cannon when you can be 4k hp and only do like 80 dps less..
Idk I'd probably do something like Juggernaught reduced smite cd by 15 seconds upgrade 0/21/9 masteries and then i'd do like:
Sheen -> Randuins(prioritize health first because its effective early to ap and ad) -> Righteous Glory (a new item it's a combination of shurelyas and randuins active and its like a roa that doesnt stack for bonus's) -> Triforce -> Locket or thornmail -> optional (damage, Ga, Tanky, Whatever)
Strategy is just like this :
Randuins is really good on vi for when you ult in you can use the randuins active and etc.. etc.. the randuins paired with the righteous glory is stupid... you can shurelyas your team toward whoever you're ulting and then slow them by 110% when ur ult lands.. and u pop the shield and randuins..
Sheen is just for early damage with Q and then finish later. Overall every item in that build gives you hp... so you can either get thornmail or locket.. locket is better unless you're really getting shredded and you need thornmail. if you're vs a snowballed apc and a scaling adc you might wanna consider locket and ninja tabi instead of mercs because ninja tabi is actually a really broken item when combined with a randuins