You can stop and have the sword stop with you without stopping it with your hands. If you have fine hair you might want to wear a headdress when doing this unless you're willing to dump a can of aqua net on your head. You want to create a lot of friction between the sword and your head. It has to overcome this friction in order to keep spinning when you stop. The faster you spin, the greater the friction will have to be to keep the sword from going propeller on you. I think one of your main problems is that you're using two swords with different masses and balance points (and it sounds like one of your swords has problems with the balance point). If you're doing double-sword balance it makes life a lot easier to use two identical swords. For all balancing the key is making sure the prop balances in one point, and that if you dropped a plum bob from that point it would hit the ground making a 90 degree angle between the floor and string. When it's on your head (or shoulder, hip, or leg) the balance point should still be perpendicular to the floor. If it's off, the prop won't stay put. The bends in your first sword are probably keeping it from balancing it properly. If it's not coated with shiny stuff you can usually bend them back into shape with your bare hands (or get a muscular friend to do it).

Thats a good idea! Yaaa!