Complex sentence: Even though his hand was merely scratched, Thanatos felt so offended and humiliated, that lost his temper and swore that Seiya woulnd't live any longer, and launched his attack on the Saint, stomping on his head, with murderous rage.
Split into simpler sentences: Even though his hand was merely scratched, Thanatos felt so offended and humiliated, that he lost his temper and swore that Seiya wouldn't live any longer. He launched his attack on the Saint, stomping on his head with murderous rage.