Ned was able to learn the spell Oblix Peruro.
Now with the elementary spells he memorized, Ned would have the chance to learn all of them. But he was limited only to two elements: fire and wind. And the level of spells was that of elementary. Meaning, the spells the book was offering were only bound to be used by beginners, that of newly discovered mages. Which was only useful if Ned was learning and limited to use within the confines of beginners.
Even though Oblix Peruro was a defensive spell that of the tier 3 fire spell. Its power, according to the book, was only beneficial to Hunters ranked from Wood to Bronze.
The only difference between the spell Ned conjured and the book was that it was him that conjured it. Making even the measly Fireball a powerhouse.
Recalling the spells he memorized, Ned had an idea: to create his own spells.
He's got defensive spells, next he needed a stronger spell.