From what I have heard, Rittersteel is half-decent to hang on a wall, but can't hold an edge while cutting air. They are soft, but not especially strong or durable either (a sign of poor quality steel and a mediocre temper). I would advise against getting them.
Kenkaku, all tempered steel, when bent, will spring back to shape (within reason, of course). This goes especially for swords. I would not suggest doing it repeatedly, but it is very hard to snap a good sword simply by bending it by hand.