Continue talking to Richard and he'll say he had planned to meet his friend Valinwe in Aldcroft after he had recovered the keep's treasures. Tell her what you found and what happened to me as well. Sure she'll be interested in what's been discovered. Like all members of the Mages Guild, she's always been more attracted to stuffy old books than to gold and jewelry.
Travel to Aldcroft, and find the evoker at the Aldcroft Mages Guild and give her the Dresan Index. She is very happy for the news about the Vault library, but is sad when she hears the news about what happened to Richard. He was a dear friend to her and she will miss him. Give her the Dresan Index to make her even more happier, as the information in the keep will be invaluable to their scholars. She gives the Vestige some for their trouble.