Joseph Baena

Arnold Schwarzenegger's love child grabbed a massive sword and a leather loin cloth ... and sent one helluva Halloween message to his dad -- by dressing up as Conan the Barbarian. 14-year-old Joseph Baena hit up Frightfest at Magic Mountain in California last night ... donning the costume made…

Arnold Schwarzenegger's love child Joseph Baena hit the Malibu surf for some boogie boarding ... less than a month after Arnold's other 13-year-old son Christopher seriously injured himself doing the same thing. Interesting fact: these pics were snapped over the weekend ... less than a mile away…