Though, the sword he uses isn't Rebellion, it's the Force Edge. His father's sword.
It is the convenience of a custom model.
Also... I think it would be best to avoid taunt moves, because...
1. CPU will never use them properly.
2. In WIFI battles, a player's taunt message will come up.
1.I think it is very long animation and be lost if Vergil get damage and more. so it can use safely only after he killed other chars.
2.I don't assume that who use on WiFi, sorry.
Also... If he's gonna have jump canceling, you should make sure these moves don't work when the foe shield them somehow. Or make them very punishable if used poorly.
Don't worry, I already know the way not responsive to shield.