I have been trying to figure out what the answer to this quest is, but I have had no luck . The question is, I must find the answer to Gin-Wulm's question What does the name Hazadir mean to you? He hinted that a book in the shop First Edition may have the answer. Plz help

You have to buy the armorers challenge from the fist edition, as a bonus it's a skill book.

There is also a copy on a shelf on the second floor of the Cheydinhal Fighters Guild hall.

Thank you all for your help

You don't even have to buy it. You can read "red hand" books without penalty, as long as you don't take them. It's the point where you take the book, that becomes the start of your troubles.