[Suggestion] Updating Essence Reaver: Giving AD Casters and Assassins a new item path

So we all know Essence Reaver, while well intentioned, is a bit clunky in practice: it comes into its own rather late into the game, competes too closely with Blade of the Ruined King and/or The Bloodthirster for sustain + damage, and generally is too niche to be worth the gold you have to drop for it. There's simply always a more useful option.

What if we really mixed things up though?

Below is a suggestion for a mid-game item called Aether Blade, which transitions into a NEW Essence Reaver for the late-game. It's designed to give AD-based spell-casters the mana and damage they need to thrive in the mid-game (at the expense of the raw damage or great sustain they might be able to get elsewhere), while offering a competitive end-game item for those who rely on spell-casts: while the raw damage might not rival that of Infinity Edge or The Bloodthirster, this version of Essence Reaver grants a few appealing things: the ability to easily hit 40% Cooldown Reduction with just masteries and Boots of Lucidity, a hefty chunk of armor penetration so your abilities hit harder, and a great form of mana sustain to make sure you can keep up your harass from now until Doomsday.

Thoughts and opinions are greatly appreciated: I've approximated the numbers, but I really need the community's input to decide if the stats are worth it (i.e. would you buy this on, say, Urgot, Lucian, Pantheon, Talon, Corki, etc.), or if the item is too aggressively costed (it's gold efficient without the passive or the armor penetration, mostly because it's an unusual item with niche appeal, and you have to give up reliable health sustain if you get it early).

Anyway, here are the items:

Aether Blade ***Build Path ***– Sapphire Crystal + Longsword + 490 gold (total cost: 1250 gold)

 +20 AD  +200 Mana  +10% Cooldown Reduction

***Unique Passive ***– Essence Thief: You regain 4% of physical damage you deal as mana (half for AoE abilities).

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Essence Reaver Build Path – Aether Blade + Brutalizer + 613 gold (total cost: 3200 gold)

 +60 AD  +250 Mana  +20% Cooldown Reduction  +25 Armor Penetration

Unique Passive – Essence Thief: You regain 8% of physical damage you deal as mana (half for AoE abilities).

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Thoughts? Suggestions? Comments? Criticism?

Would these items tempt you on a spell-heavy Marksman or AD Assassin? Why or why not? What could be improved?

Thanks in advance!

-The Djinn