I dislike the idea of breaking weapons, but if you do it, weapons should have separate stats for damage done to own weapon while attacking and damage done to own weapon while defending.
A sword would be very hard to break by parrying with it. It will get damaged quicklier if you are attacking with it yourself. Axes should break rather easily when parrying because of the wood hilt. However, the axe will almost never break by attacking with it. A lance couched from horseback should break immediately.
A sword would also have a very high resistance: a lot of damage needs to be done before the sword will actually get damaged.
But I still hate the idea, but I wouldn't hate it as much if the above is implemented. More weapon slots would also be required.
Especially for multiplayer I detest the idea. For single it is acceptable. Not fun, but acceptable.
