I bought a SOG Spirit - it is a hand-held metal spearpoint on a nylon handle. You can also attach it to longer threaded handles and use it as a spear.
It is, in all honesty, more novelty than weaponry, but I always wanted one ever since I saw these, and so I bought it. It is fairly well-made, but in a fight for your life scenario, it could do considerable damage. But I think it would be a one-and-done use weapon - if you had to rely on it for multiple strikes, I think it would break. But it still has some inherent potential, and it does look kinda cool, which is important, especially given the fact that it will almost certainly never be used in anger (just keeping it real, folks...).
I go snorkeling for flounder using a trident gig, and I have gigged some pretty big flatties that put up a hell of a fight, and I thought it might come in handy for dispatching a fish quickly.
I also bought a mini-hacksaw, with extra blades. It is really hard to schlep around a bolt cutter, but a quality mini-hacksaw could really come in handy. It is the lightweight shaped metallic round stock model used by professional plumbers, and it could cut through metal if you have enough time, or no other choice.... For under $20 with 10 extra blades, I couldn't pass it up (plus I had a plumbing project I needed it for, so what the hey...).
Spear and a hacksaw, my new adds.