1) Saw: simply wrap a cloth around for a simple handle. For a more sophisticated handle cut a small branch then cut a slot along its length half the width deep and wedge the blade in.Often a dry piece of wood will have useful split in allready.  A cloth wrapped around this will make it more comfortable. If the blade is used for cutting thin items then only a little needs to stick out and the rest is well supported. with a cloth or grass fibres over the teeth the blade can have a binding to hold it all together.