10 seconds is completely broken, and entirely to long of a duration to deal with any burst caster. That would help out bruisers more than melee carries really - not to mention AD is something that's significantly less cost effective on most melee carries over more, seeing as they generally have solid base AD scaling and a rather powerful AD steroid. Such a Black King Bar item would offer no counter-play to champions that are reliant on CC and abilities as well - if you thought seeing quicksilver sash was disheartening to Malzahar players before this would completely invalidate not only Malz but just about all AP carries (Ahri is about the only actual mage that isn't CC reliant for escaping). 2700 gold is to cheap for that kind of power as well, and would likely result in a kill upon each activation, snowballing you hard enough each time to get another kill in a window of time 1 second shorter.
Originally Posted by The Lord Impaler
Riot can do one of three things, 1) do across-the-board nerfs to these effects when Ranged, similar to how Spell-vamp is cut to 1/3 for AoE spells. 2) have a large number of items give lesser effects to ranged champs (like recent ice-born-gauntlets changes). or 3) permanently split off a number of superior items as melee only.
Or they could 4) give melee carries noticeably higher than average base attack speeds - which would effectively multiply all damage scalers and things like life steal on them better than the next guy, solving problems of cost-effectivness without getting to complicated concerning bruisers and ranged attack damage carries. It also makes plenty of sense - smacking something with a katana, cutlass, or rapier should be considerably swifter than operating a cannon, shotgun, or sniper rifle - or lamp post, great axe, or great sword. Turns out Maokai has better attack speed than Fiora, Trynd, Yi, or Gangplank though, and the difference in attack speed from ranged to melee weapons is essentially non-existent.