slowness vs unskillfulness

slowness and unskillfulness both are nouns.

Word	Noun	Adjective	Verb	Adverb
slowness	Yes	No	No	No
unskillfulness	Yes	No	No	No

As nouns, unskillfulness is a hypernym of slowness; that is, unskillfulness is a word with a broader meaning than slowness:

slowness (noun)	unskillfulness (noun)
a rate demonstrating an absence of haste or hurry	a lack of cognitive skill
lack of normal development of intellectual capacities
unskillfulness resulting from a lack of training