I know this topic was posted on these boards a year or two ago, but I never got to see the opions. I haven't played DMC 2 yet, but am planning to, so I don't know what swords he has in those. The Soul Reaver, all various incarnations/enhancements aside, has essentially remained the same in terms of basic abilities and properties throughout the Legacy of Kain series.
I believe as a fighter, Dante wins heavily. However the contest is not based on fighting skill alone, but on overall skill and ability, and here I think Raziel may have a slight advantage due to that fact that he can not die, and that Dante's devil trigger would eventually run out after repeated assualts on Raziel, only to have Raziel return to the material plane time after time. The Soul Reaver and Alastor, I believe the Soul Reaver has the edge. Alastor cannot fatally harm Raziel, whereas the Reaver could swallow Dante whole.