One tactic that is common to almost all forms of sword fighting is to attack the hands. A tsuba is not so much a "sword catcher" as it is a STOP to prevent the opponent from simply sliding his blade down yours and lopping off a thumb and a finger or two. The idea obviously being, "If you can't hold the sword, you can't fight with it."
In a sword on sword fight, your hands are the body parts most likely to be hit. They're out there in the middle of things and they are the body part closest to the opponent. Even with a pappenheimer hilt, good quality, leather gauntlets, and a rule stating that hand hits score no points, (for the sake of safety) I've still managed to acquire a few interesting scars on the backs of my hands.
Guards and tsubas are worth their weight in gold when facing another sword.
Tactically speaking, the modern soldier armed with a sword is unlikely to ever face another swordsman, so the usefullness of a guard is probably negligable, but then so is the sword itself.
If I had to pick a "tactical sword" to carry into a modern combat environment, it would most likely be a good quality machete.
A good machete is a great tool that makes a good weapon when needed.
or
A machete makes a decent sword, a sword makes a lousy machete.