I recomend you check the latest Eldar Codex, lots of things has changed in the Eldar codex, Check the weapon special rules, range, Armor saves, Exarch wounds and in general Aspect special rules. Since most aspect do not need an Exarch for special powers.
Striking Scorpions, Fire Dragons, Dark Reapers, Warp Spiders, Shining Spears and Exarchs all wear Heavy Aspect Armor, which is a 3+ like Marine Power Armour.
ELDAR - ANCESTRAL HEAVY ASPECT ARMOUR ¤ 10000 RTP Those Aspect Warriors who bear the brunt of enemy fire favour more heavily armoured defense. The Fire Dragons, Dark Reapers, and Striking Scorpions don these heavily plated versions of their own Aspect armour, as countless warriors did before them. Each suit of Ancestral Heavy armour bears the psychic touch of those who came before; forever marked by the glory, triumph, and even failures of those who lived, fought and ultimately died clad in this gear, for only in death does the armour find a new warrior to protect. This is a visual customization for the Eldar faction item that replaces heavy wraithbone armour. Type: Armour (Chest) You are correct.
All is correct, except the Exarch bit. To avoid delays in Mixed armour save rolls for the table top. The Exarch now has the same armour as the rest of the unit. As compensation they got 2 wounds instead of 1. Exarchs are still badass . Way better then those Veteran sergeants, sternguard/vanguard and command squads .
Unless we speak about lore, then they aren't as badass as your generic Space Marine... I dislike reading Wh40k books.
Thats because in the novels marines have these Movie Marine stats and are not done with table top Codex stats. I remember many a disappointed marine player after reading the "fluff" in the starter set and getting annihilated turn 2 on their first game (happens to all of us).
IIRC they are categorized as "Elite" troops and have an upkeep of Requisition Points to field, which is both balance and lore wise correct. They can't die after all, unless the plot demands it.