Staff (wood advice)

[Luci_ferson]

Ive been thinking of making a staff.
since i have pretty bad arthritis and it would help with walking in the colder months anyway.
however if im going to carry a stick, it may as well be a weapon too.

my plan was to make it just short of shoulder length from the floor.
and use a piece of wood where I could carve an nice round fist sized ball.
I would like this made out of a strong but semi flexible wood so that it has some spring when needed making the fist sized ball on the end move nice and fast and spring loaded when needed.
you can imagine my intended purpose.

any suggestions for a good wood that Would have these properties.
yet remain strong.