I'm pretty sure that fight wasn't part of the trial (in the lore). I mean, he almost let us go after we defeated the vrykul kings.
We fought him so we could get "our names to echo in the halls for eternity" or something. It's like a combo, claim the Aegis and get a chance to make the vrykul hear "Xxnoobzlayerxx" forever.
Through the use of swords and fel magic - or they just let him in, he's the goddamn God-King after all.
What I really don't get about the dungeon is that Eyir gets all mad when Alliance goes there even though Greymane saved her butt.