TarkatanDentist
Noob
The original Soul Edge, released way back in 1997, had a lot of interesting fighting mechanics that got dropped in Soul Calibur, then never picked up again. Of particular interest the weapon gauge which, if depleted, meant you had to manage without a weapon for the rest of the match, plus the Critical Edge attacks that used a third of the gauge (a feature which did eventually return, albeit altered, in SCV). There were other somewhat quaint features as well such as the clash system (if two attacks hit at the same time, it became a rock-paper-scissors scenario regarding who had the advantage). Plus each returning character's move list ended up being changed a lot from Soul Calibur onwards... Hell, you could just re-skin the characters, give them different names, and most people probably wouldn't even notice . 
In all seriousness though, with a bit of tightening up I think that Soul Edge's fighting system could work really well. With slightly more fluid movement (I'm thinking Tekken-style sidestep + sidewalk, rather than SC's 8 way run), running at 60 fps, and some other changes here and there (e.g. slowly recovering weapon gauge, different hand-to-hand move lists from character to character etc.), I reckon it could work really well.
In all seriousness though, with a bit of tightening up I think that Soul Edge's fighting system could work really well. With slightly more fluid movement (I'm thinking Tekken-style sidestep + sidewalk, rather than SC's 8 way run), running at 60 fps, and some other changes here and there (e.g. slowly recovering weapon gauge, different hand-to-hand move lists from character to character etc.), I reckon it could work really well.