ascendent vs ascendancy

ascendent and ascendancy both are nouns.

Word	Noun	Adjective	Verb	Adverb
ascendent	Yes	Yes	No	No
ascendancy	Yes	No	No	No

As nouns, ascendancy is a hypernym of ascendent; that is, ascendancy is a word with a broader meaning than ascendent:

ascendent: position or state of being dominant or in control
ascendancy: the state that exists when one person or group has power over another

Other hypernyms of ascendent include ascendance, ascendence, ascendency, control, dominance.

ascendent (noun)	ascendancy (noun)
someone from whom you are descended (but usually more remote than a grandparent)	the state that exists when one person or group has power over another
position or state of being dominant or in control

ascendent (adjective)	ascendancy (adjective)
tending or directed upward
most powerful or important or influential