Originally Posted by Xypherous
AS/Armor benefits such a small subset of characters that I'm kind of hesitant on this. A truly decent AS/Armor item might necessitate the nerfs of already existing balanced characters and bind those characters to that item.
That's my main worry - as AS/Armor/Proc doesn't open up new gameplay for these characters - it just means that they just get more powerful with the item - which is an item that directly affects balance.
Unless the main focus of the item wasn't the AS/Armor part - it might be feasible to dance around the niche problem - you run into some oddities then, releasing an item with stats that people want but a playstyle that people don't necessarily want to be forced into.
All melee carries would benefit from an AS/Armor item. Ranged carries who want to be stronger in the laning phase would get it instead of Zerker greaves.
Armor, especially armor tied to damage stats like crit, as, ad, is a great way for champions to win against those building pure damage.