this fight is like a bear fighting a bear trap... revan being the furrier of the two.
If it's Revan during the Mandalorian Wars, then he is at a distinct disadvantage for one reason:
The army of the Galactic Republic during the Mandalorian wars battled Mandalorians, who preferred straight fights and epic battles. Traya's shtick is to stick the knife in the back and turn it, turn it and turn it.
Traya and her assassins can blind others to her presence, particularly Force Sensitives. Traya's assassins also exploit the Force, becoming significantly stronger when in the presence of Force adepts. documented -overwhelming- success of her assassins on the Harbinger suggest that this is not even a fight but a slaughter. Jedi strength within Revan's forces as well as the mass of his troops are nullified by the fact that they aren't fighting their intended enemy but instead a ghost, masters of subterfuge.
In a one-on-one fight, hypothetically I feel it would be a very close fight because of Revan's power in the force. However it may be entirely possible for Kreia to simply kill him by severing his connection to the force, as easily as she did with the three jedi masters at Dantooine, or to create a Force bond and damn the both of them if she dies. Depends on the setup.
The Kaggath fight goes to Traya because she is not the predictable enemy that the Mandalorians were. Her assassins, with and without her, exponged the Jedi from the galaxy. Revan, as we saw at the foundry, is just more prey totally dependant on the Force.
You make a good point.