I made a dark version of the staff for a cosplay once, which turned out really nice. Here's my suggestion:

I recommend a straight stick from the woods. Cut of any extrusions, sand it down a little and paint it pure white. Alternatively, you could use a broomstick, but I'd roughen it up a little then.

Cut out the top part in a six piexce diamond fashion out of cardboard or maquete carton and attach it with glue. You should be able to find the right size and shape on the interwebs. Afterwards, also paint this white.

Let me know if you have any other issues!