The meaning "slope upward" is from 1832. Related:Ascended;ascending. An Old English word for it wasstigan(seesty(v.)). ascendancy(n.) "dominant power or influence, state of being in the ascendant," 1712; seeascendant+-cy. ascendence(n.) ...
"the act of ascending," but used from the start in English as a synonym of ascendancy… See origin and meaning of ascendance.