As an islander, and being from a country where firearms are almost non-existent, except for about a dozen wild guns cycled through local gangsters and those used by the Police and Riots Unit (our equivalent of a military although nothing as close), knives are the best we have for defense and they're also great tools. I've got a small Diving knife, from Saeko Dive I believe. It's about 16-17 cm long, that's about 6-7 inches long, the blade is half the length and it's very sharp. The upper back of the blade is dented like a saw and the lower part has a small but super-sharp groove for cutting wires or algae in the sea. Plus it's very comfortable to wield. I'd suggest you try one. There are bigger versions too. They're good for anything from close-combat to surviving in a forest or the sea. Or really anything requiring cutting,sawing or chopping and such