Complex sentence: Although the sword's official name is Anaklusmos, it is referred to as "Riptide" during most of the series.the sword has it is seen in book three (The Titans curse) does not harm mortals only immortals.
Split into simpler sentences: Although the sword's official name is Anaklusmos, it is referred to as "Riptide" during most of the series. The sword has it is seen in book three, The Titan's Curse, does not harm mortals, only immortals.