ok good, just to get that straight....carry on, please.
There's actually two different kinds of weapons called "sword breakers", that work on different principles. One is Chinese:
Originally Posted by jspeedy
It's a heavy weapon with a heavy cross-shaped blade, and when you beat on someone's sword with it, it could cause it to bend, break, or get knocked out of their hand, then you finish them with the point. Against a Chinese straight sword, I could see this working.
The other is a European parrying dagger with teeth on the spine that could trap a blade. It looks like this:
In theory, you might be able to snap a blade in this way. Probably not, but by the time these were a thing, swords weren't very robust, so it might be possible against a sword like this:
I think the greater advantage is that while their sword is momentarily trapped, yours is not (a sword breaker would be held in the off hand as a companion to your own sword), so you can get an attack in that moment.