Any bar of steel a few feet long and an inch or few inches thick is going to be pretty hard to break unless it includes a large flaw such as an included impurity or a weak weld, and then you still have ot hit it in the right spot, and very hard, and it has to not be free to move so the force doesn't just get wasted on knocking it back instead of breaking it. How breakable would you expect any other equivalent-sized bar of steel to be while held in the hands? At the very least, you'd have to have it braced against something solid while you hacked at it.

Descriptions of damage to European swords from the time they were really used describe them getting bent, not broken, and sometimes bent back again and still used. And it was generally done by someone or someone's horse falling on it or some other such oddity, not by a blow from someone else's weapon in open air. (A katana might be more likely to break instead of bending under such circumstances, but the key is the abnormality of the circumstances. It just doesn't happen in fights.)

Hitting it on the side is best for knocking it out of the way if its user is attempting a cut, because that creates the biggest change in the sword's direction of movement. If you intend to damage someone's blade, though, the best place to hit it is the front. The edge is harder than the spine (back), which is good for cutting but makes it more brittle than the somewhat softer but more shock-resistant spine. So the front is the place that's most likely to lose a chip or flake. That means that if you see a blunt force coming and you need to block/deflect it with your sword instead of just dodging, you'd actually want to turn your sword to the side for the impact.