I've made a few padded staves and pole-arms.
What I've done is used heavy (1/2" landau)padding on the striking ends, plus open cell thrusting tips at least 3", then use the thin 1/8" microcell puff in one layer around the haft, plus another layer in areas likely to be striking zones. I usually go over the inner 'haft' part with electrical tape, and make a couple of grips at the most ergonomic grasping points with hockey stick tape. The striking ends I leave covered in duct tape.
I have a staff I made but it's in New Orleans or I'd show a photo. You can get kind of an idea of how to do the haft though from the haft of this long-handled axe.
If you look close you can see how there is one 1/8" layer padding at the short end, and two layers closer to the axe-head.
For a safer version you can use pool noodles instead of the landau or blue camping pad foam. With padded weapons it's always a tradeoff between realism and safety.
JR