I very much agree, most of what I have seen written on 'sword breakers' is largely hyperbole, and Egerton Castle noted that most of these toothed type daggers in Europe were imaginatively presumed so. According to him these actually seem to be from later when left hand daggers had fallen out of use.
It is possible that the fragile rapier blades might have been broken in phenomenally ideal circumstances and rare cases, but to accomplish this as a tactical manuever would take the cooperation of both combatants.
In Indian arms, like with African arms, both of which have curious and innovative forms, as Christopher Spring noted, there is a western propensity to need to discover or 'invent' possible uses for these unique forms.
It seems to me there is far less chance of breaking a dagger blade of any kind as there is far less mass which is less susceptible to the dynamic flaws which would allow breakage. Naturally there are bound to be exceptions, but personally I have never heard of anyone trying to break a dagger blade
