Complex sentence: Triskaidekaphobia may have also affected the Vikings--it is believed that Loki in the Norse pantheon was the 13th god--more specifically, Loki was believed to have engineered the murder of Balder, and was the 13th guest to arrive at the funeral.
Split into simpler sentences: Triskaidekaphobia may have also affected the Vikings--it is believed that Loki in the Norse pantheon was the 13th god. More specifically, Loki was believed to have engineered the murder of Balder, and was the 13th guest to arrive at the funeral.