Tavion is like a one handed blue stance... It's fast like blue, but strong like yellow...
Desann's stance is also one handed, and is fast like yellow, and perhaps even stronger than red, but I don't know that for sure
They look a bit different, kind of a nice twist after playing the game with the original stances
At least, that's what I've gathered... I could be wrong
i'm sure teleguy will correct me