But in episode three, Aegon dons a set of Valyrian steel armor that he says belonged to Aegon the Conqueror. It's this armor he appears to wear to the battle. We know from "Fire and Blood" that ...

His armor even melted into his flash on his left arm. Aegon did recover enough, but he didn’t keep his crown at first. Rhaenyra eventually became Queen of Westeros and sat on the Iron Throne.