丈 shows a hand gripping ten — ten spans, an ancient unit around 3.3 meters. A grown man measured about one 丈 with arms raised, so 丈夫 'one-zhang man' came to mean a full adult male, then a husband.
丈夫 is husband; 大丈夫 is a 'great man' — someone of real character, as in Mencius's line that a true 大丈夫 cannot be corrupted by wealth or bent by force. Your wife's father is 丈人 — the man you measure up to.
A hand holding TEN spans — the full MEASURE of a man: HUSBAND.
丈二和尚摸不着头脑 'a 3.96-meter monk whose head you can't reach' means utterly baffled — confusion measured in 丈.