unmanfully vs unmanly

unmanfully is not an adjective while unmanly is an adjective.

Word	Noun	Adjective	Verb	Adverb
unmanfully	No	No	No	Yes
unmanly	No	Yes	No	Yes

As adverbs, unmanfully and unmanly are synonyms defined as:

unmanfully (adjective)	unmanly (adjective)
	not possessing qualities befitting a man
	lacking in courage and manly strength and resolution; contemptibly fearful

unmanfully (adverb)	unmanly (adverb)
without qualities thought to befit a man	without qualities thought to befit a man