Pronunciation note: The i is pronounced with a long e sound. The o is a short o sound. The e is silent. The level of pretentious French accent used to pronounce it is up to you.
Spelling note: There is no c in sissone. It has nothing to do with scissors.
Like its other A-dance brethren, the sissone is too anemically valued to be a countable skill on floor, but it has gained some new life when performed out of tumbling passes for connection value, or (from 2014-2016) out of dance elements for don’t-downgrade-that-previous-terrible-dance-element reasons.