1. Who was the first to initiate the handshake? 2. Who was the first to speak Arabic? 3. Who was the first to craft armor? 4. Who authored the book "Al-Kaba'ir" (The Major Sins)?

We apologize for not answering competition questions, as they affect the website and its workflow, and usually do not result in a Shari'ah ruling. As for your fourth question, a number of scholars have written about major sins, including: Shams al-Din al-Dhahabi, Ibn Hajar al-Haytami, and Sheikh Muhammad ibn Abd al-Wahhab.