How do I attach crystals to a shaman stick without using adhesive?
Adhesives based on pitch (e.g. resin from pine tree sap) and beeswax have been used for millenia.  This makes a hot-melting glue that's strong enough to secure knife handles.
One example is Cutler's Resin. Here's one of many recipes; other similar compounds include stone dust (e.g. ochre), and were used in ancient Eqypt (an old answer of mine).  The effect of the beeswax is to soften the pitch, while stone dust (or presumably wood dust) is used as a filler.
I reckon you might want to slightly inlay the crystals to make them more secure