Have you gone to Aleroth and done the quests there? IIRC (it's been awhile since I played), there's three things you need to get into the Hall of Echoes, and I think the Shield you get in Aleroth. There's a book in your inventory, under quest items, I think it's called "Maxos Book" maybe. Anyhow, whatever it is called, that book has information about how to get to the Hall of Echoes, and where you can find the items.
To get to Aleroth, you have to
A) Find some zeppelin parts (Rudders, Compasses, Stabilators) - they are in some of the Wyvern Nests in the Fjords, so you'll have to hunt around a bit.
B) Go to the Champions Harbor, to the roof/Zeppelin dock. There's a guy there who you have to talk to, who needs the parts so they can repair the Zepp.
C) Once you've given him enough parts, you can talk to the chap on the ramp up to the Zepp to book passage to Aleroth (unfortunately, there's no flying scene - you just load into Aleroth).
There's various things you'll have to do in Aleroth, but the key thing is that you have to talk to Zandalor (the old Wizard you run into throughout the story), and then, IIRC, you have to help defend Zandalor while he shuts down some demon portals or something.
I think once you complete that, Zandalor can give you the shield. I might be misremembering, though. You get *something* you need in Aleroth, anyhow.
for you help 
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