Isn't any umbrella obviously looking like a weapon? Am I the only one who role-played it's a rifle as a kid (and still do as an adult, sometimes)?

And then, a well-made long umbrella would effectively double as a cane, at which point it fits well in the martial art of Bartitsu.

https://en.wikipedia.org/wiki/Bartitsu

EDIT: see also Bartitsu reference and other applications here: https://en.wikipedia.org/wiki/Umbrella#As_a_weapon_of_attack.