Yeah, I find when mockfighting with swords and large shields, that you always want to go for a stab but often this isn't an option. For stabbing, you have to either sneak under the opponent's shield or over it; you go for the throat or the belly. IIRC, the Romans did the latter.

For big heavy slashes, I think an axe would generally be better, but swords were better balanced, and even a sword with a rounded tip, if the tip was sharp, could stab into a torso.