My point was about the chain, not the sickle. The sickle will break on the shield if blocked. kusarigama is average of 8 feet in length and also requires 2 hands to use, if you make the chain any longer then that it is easy to intercept. That distance is coverable in a lunge. As soon as the ninja lets go of the chain, you lunge at him. If the chain hits you, it doesn't matter as you have already covered the distance to him and you're either hitting him with your shield or sword/pike.
Senbon have an incredibly short range unless they are anchored into an object which then becomes shield fodder, or you can counter by throwing the pike or dagger then close the distance with shield/sword