Complex sentence: He was known as a valiant, competent military leader and individual fighter who was courageous and generous but, on the other hand, was also prone to the sins of lust, pride, greed, and above all excessive cruelty.
Split into simpler sentences: He was known as a valiant, competent military leader and individual fighter who was courageous and generous. However, at the same time, he was also known to be prone to the sins of lust, pride, greed, and above all excessive cruelty.