Complex sentence: Slade is a Vandel Buster and a rival of Beet's whom he has known since his training journey.like Beet, he is highly skilled in the use of spears, which has been developed by the 120 bouts he and Beet have fought.
Split into simpler sentences: Slade is a Vandel Buster and a rival of Beet's whom he has known since his training journey. Like Beet, he is highly skilled in the use of spears, which has been developed by the 120 bouts he and Beet have fought.