Archives of the Invisible Sword
CHRONICLES OF IXIA
According to the author’s website, the Chronicles of Ixia have been written as three trilogies, which all interconnect. The Study series and the Soulfinder series are narrated by the same protagonist.
If you are interested in reading these books, I highly recommend visiting the author’s website so that you can also read the short stories she’s written, as they do add a great deal to the overall plot of the books.