Originally Posted by
Lyth
I don't think it's necessarily as clear cut as that. Omnislash may have set the series precedent for high-speed Greatsword combat, but Lionheart (and later, Army of One) followed suit with Gunblades. I don't think the distinction is clear cut.
That being said, I think that there are little stylistic distinctions that you can draw between the two fighting styles. I would expect individual attacks from a Gunblade, while fast, to be slightly "burstier", while I'd expect a Greatsword aesthetic to go more along the lines of multi-hit strikes and after-image effects. I also would envision Gunblades to be a more mobile combat style, with abilities that help you jump into and out of combat on demand. Gaius and Regula are both fairly mobile when you fight them.