Exactly as it says. The middle of the saber, the hilt, could bend. So when needed, the saber would resemble "V" or "U" or even ~. The weapon would be mainly used as a regular two bladed saber, but this bending option would give more freedom of movement. Also, one could sort of throw the other blade towards the enemy, as the hilt would also flex a bit. There is a traditional, realworld weapon, which could explain my idea, but my memory fails me again.