Elven mages didn't attempt to cast from Meitre's scrolls until the final year of their apprenticeships, and humans didn't even try until their apprenticeships were completed. ( In arcane academies, such as those in )Dalaran and Silvermoon, it was established policy that apprentices not be allowed near them. The students of Scavell all read the scrolls, though only Aegwynn did so with permission, and was able to gain mastery over the spells and rituals in the scrolls in record time. The scrolls covered magical topics ranging from transmutation to advanced ward-penetration, and likely a number of other subjects.
For much of Aegwynn's tenure as Guardian, the Meitre scrolls served as a sort of advanced guideline for magical theory; however, by the time that Jaina Proudmoore was training, the scrolls had been largely laid aside, and the only known copies were lost when the Violet Citadel was destroyed.