manfully vs manly

manfully is not an adjective while manly is an adjective.

Word	Noun	Adjective	Verb	Adverb
manfully	No	No	No	Yes
manly	No	Yes	No	Yes

As adverbs, manfully and manly are synonyms defined as:

manfully and manly: in a manful manner; with qualities thought to befit a man

manfully (adjective)	manly (adjective)
	possessing qualities befitting a man
	characteristic of a man

manfully (adverb)	manly (adverb)
in a manful manner; with qualities thought to befit a man	in a manful manner; with qualities thought to befit a man