The Weave
The Weave is a magical phenomenon in which words, song, and stories have the ability to cast spells and produce magical effects. They are also often called 'Words of Power', and those who can control them are sometimes called 'Weavers'.
Compared to traditional arcane spellcasting that is popular in Aisoa, tapping into the Weave is less easily replicable. The fickle and unpredictable nature of magic is what makes mastering the Weave just as much as it is what makes it powerful - what may be nearly impossible with classical spellcasting could be quite easy in comparison.
Weavers tend to be taught by a mentor, or more rarely in bardic colleges. Study of the weave is quite individualized, and mastery of it without guidance tends to be quite difficult.