man-at-arms vs soldier

man-at-arms and soldier both are nouns.

Word	Noun	Adjective	Verb	Adverb
man-at-arms	Yes	No	No	No
soldier	Yes	No	Yes	No

As nouns, soldier is a hypernym of man-at-arms; that is, soldier is a word with a broader meaning than man-at-arms:

man-at-arms (noun)	soldier (noun)
a heavily armed and mounted soldier in medieval times	a wingless sterile ant or termite having a large head and powerful jaws adapted for defending the colony
	an enlisted man or woman who serves in an army

man-at-arms (verb)	soldier (verb)
	serve as a soldier in the military