Captain Hook had only WAN arm.
Your arm is an organ you use for putting on your crown in the evening. Plus arms have fingerprints at the ends!
arm. Also, to be good at something, as in, "xxxの 腕 が いい!" "She's good at xxx!"
armband. Anytime you see an unemployed grand-dad with an armband, you can be sure he will poke his nose in someone's business and try to wreck their fun:"No smoking!" "No bicycle parking!" "No hammocks!"