>>1597073>hidden blade walking stick>survival staff>walking cane with hidden spear/bladeThere's like 100s of them. Pick a use, there's ones for defense, hunting terrestrial game, and hunting aquatic game. The ones for defense are normally "hidden" while the others may just have a sheath over the spear head. If you don't mind people knowing it is a spear, just get a, "Cold Steel Assegai Spear with Long Shaft." (left-most spear in pic) If it really does need to be hidden for some reason then get one of the "survival" ones since those will be a bit better than the cheap knock offs. Though, if you can find ones sold my martial arts companies they may be structurally sound too.
Theoretically, walking around with a hidden blade can get you into trouble. Either because it is a hidden blade and those might be illegal in the area you are walking through or because you may be targeted by someone since they only see a stick. Though, just having a stick can dissuade such problems. Having an obvious weapon like a spear walking stick would pretty much prevent all problems with anyone except those who are really fucked in the head.
Regardless, prepare to pay at least $80 for a spear and $90-$100 for a hidden one. Any less and the quality will be seriously lacking. If you need to use it, you want quality.