Lack of an AD Support Item Restricting the Meta
I don't know if there is some logic behind not having AD supports, but rather restricting them to tanks, mages, and utilities; however as far as I know I see no problem in having an AD support so long as the item isn't powerful.
A benefit of a AD support is that you are able to hold a lane even without mana. They can harass and poke, apply pressure, and zone easily without the worries of mana. Champions like Ashe and Yasuo are both my favorite champs that I would like to try in the support role. Ashe has slows and visions, aswell as a global stun; while Yasuo has poke, mobility, windwall utility, and able to become a powerhouse late game.
Here is my suggestion for a support item:
Dagger of Riches 50% mana regen 2 gold per 10 seconds Passive: Ranged champions gain ~~ 5 ~~ 3 AD, melee champions gain ~~ 10 ~~ 5 AD Unique Passive: Attacking enemy units will increase the gold. Ranged Champions gain 2% per attack, limit of 15 stacks. Melee Champions gain 4% per attack, limit of 10 stacks. (At max stacks, ranged champion will gain 2.6 gold per 10 seconds, and melee champions will gain 2.8 gold per 10 seconds.
Ceremonial Short Sword 75% mana regen 3 gold per 10 seconds Passive: Ranged champions gain ~~ 10 ~~ 7 AD, melee champions gain ~~ 20 ~~ 12 AD Unique Passive: Attacking enemy units will increase the gold. Ranged Champions gain 2% per attack, limit of 15 stacks. Melee Champions gain 4% per attack, limit of 10 stacks. (At max stacks, ranged champion will gain 3.9gold per 10 seconds, and melee champions will gain 4.2 gold per 10 seconds.
Blazed Bastard Sword 3 gold per 10 seconds 10% Lifesteal 30% attack speed. Passive: Ranged champions gain 30 AD, melee champions gain 50 AD Unique Passive: Attacking enemy units will increase the gold. Ranged Champions gain 2% per attack, limit of 15 stacks. Melee Champions gain 4% per attack, limit of 10 stacks. (At max stacks, ranged champion will gain 3.9gold per 10 seconds, and melee champions will gain 4.2 gold per 10 seconds.
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The new BC is a nice help aswell, now only zekes needs some changes(like replaceing 10%cdr with another 10-15 ad)