That's just too generic.
Just curious, do you actually play Varus?
He's one of the two marksmen I can actually enjoy playing (the other being Draven). And Varus' playstyle, as it is, feels fine and enjoyable to me. My only problem with Varus is that his passive feels entirely ineffective. It only activates after you kill an enemy, and it's a pathetically small AS buff.
Compare his passive to Ardent Censer; when Varus kills a non-champion enemy unit, he gains +20% AS for 3 seconds. A base of 0.658 means that he gains about +0.132 AS for 3 seconds (over 3 seconds, he deals 0.395 more attacks). If he kills/assists on killing a champion, he gains +40% AS for 6 seconds, or about +0.263 AS (over 6 seconds, he deals an extra 1.579 attacks).
Ardent Censer, when you shield/heal an ally, grants your target +25% AS for 6 seconds. For Varus, that comes out to 0.1645 (+0.987 attacks over 6 seconds).
Varus' AS gain, again, only happens after he kills a unit. After he has already done what bonus AS would make easier to do.
The reason I suggest something so generic is because Varus doesn't need more. People who think Varus needs more than simply swapping his W and passive are usually obsessed with the fact that he doesn't have the innate mobility that some other marksmen have, or go on about how he hasn't had his popularity skyrocket like other picks. But I'm curious; why is a generic Varus change not good enough, in your opinion?