My setting contains modified humans who live on an ocean planet with only small pockets of land. Generally, large populations of people live on these small islands but since land is so restricted, they get most of their resources from the sea in the form of fishing, diving (foraging/hunting), or underwater farming. Luckliy, the humans are able to hold their breath for a long time (over 30 minutes) and can see rather well underwater (due to genetic adaptation).
Unfortunately, the sea is not safe. Diverse threats, large and small, lurk in the deep. Everything from giant kraken to tiny piranhas love to snack on humans. That's why the humans need to defend themselves. Generally, the intelligence of the attacking creatures is primarily bestial/instinctive. Only very few underwater threats are capable of more than animal cunning.
What melee weapons or combat techniques could be used to:
- Fend off foes while diving (curious sharks and more aggressive monsters)?
- Defend ships from emerging attackers (think giant kraken tentacles)?
- Bone, wood, and fibrous materials are available in great quantity along with other materials that can be harvested from the sea such as shells, shark teeth, and coral
- Metalworking technique is advanced and complex. Alloys can be made and furnaces can reach extreme temperatures but metal itself is very rare. Metal tools, cooking instruments, and weapons are often family heirlooms and highly valued.
- Glassmaking and ceramics are suprisingly advanced. Large amounts of glass can be produced, even at high clarity
- Ranged weaponry like harpoon guns exist however aren't really man-portable but rather ship-mounted.
Thoughts I've had:
- Slashing or crushing weapons such as hammers or swords would be greatly slowed by the water and rendered almost completely useless.
- Piercing weapons such as harpoons or rapiers might be effective.
- Arm-guards or bracers which bait the creature into latching on could bring it into knife-melee range