Yeah mate, the important word I think you've glossed over is "additional". So the triumph makes 4 attacks with the martyrs sword, and ten with another profile.

The martyrs sword attacks are in addition to the 10-2 relic weapon attacks on the profile

You get 4 additional attacks with that weapon, on top of however many normal attacks it had. However you can only use that sword profile for those 4 attacks. Instead of for all 10-or-so

I'm confused with the wording of it's The Martyr's Sword weapon. It reads "
Each time the bearer fights, it makes 4 additional attacks with this weapon and no more than 4 attacks can be made with this weapon."

Model has 10 attacks.

Triumph of Saint Katherine fighting