In Season 1, we’re introduced to The Mountain, aka Gregor Clegane. He is a beast of a man in all senses of the word: ruthless, guiltless, animalistic, strong, and HUGE. Following a joust in which he was less-than-pleased with his performance, Mountain takes his aggression out on his horse. Beheading it. Because that’s what you do.
Poor Theon. The guy can’t catch a break. When he tries to be badass and behead Winterfell’s Ser Rodrik, it takes him four or five swings to get the job done. Maybe he should take lessons in removing appendages from Ramsay Snow.