A wife who sends a vase sailing at her husband's head might be considered an assailant, or attacker. Or, they might be playing a game of dodgeball with the furniture.
Assailant comes from the Latin ad- meaning "at" and salire meaning "to leap." Leap at someone and you're an assailant — someone who attacks. You'll usually hear this word when lawyers or police are talking about attacks, because most people use its synonym attacker in casual conversation. Have you ever been attacked by ants, looking down to see your foot covered in them? Think of the word ant when you spell the word assailant to remember its ending.