Well you don't have to be a force crazy monster to be the best. If he was a phsyicotically powerful and fast fighter then he would still be extremely difficult to beat.
This game doesn't seem as exciting DS as LS. LS your little crew is against an entire empire. If you join the Sith on the path to darkness you've got friends in that great empire. Which sounds more epic and exciting?
God that wouldn't sound right........Sith Lady.......takes the original title and takes away the intimidation. Not trying to offend anybody, but that really doesn't sound cool.
Or maybe they aren't at all connected or related. Perhaps their at each others necks because they are at opposite ends of their extremes. Sith Lord vs. the last Jedi Master. Wouldn't you fight constantly?
Ah....with only the slightest twist of fate there would be lightsythes instead. Then somebody would say they want a sabre. Can you imagine?
Luke: Well what is it?
Ben: It's you father's lightsythe. It's a reapers weapon....not as clumsy or random as a blaster for a more...........brutal age......your too old to use it now.