Modder xxdeathknight72xx has found a secret weapon while rifling around in Fallout 4’s files, the Harpoon Gun.
It would appear that the weapon was not meant to be included in the original release of the game, as it has not yet been found, and the animations for the weapon are not quite up to par. The weapon can be unlocked in-game by using console commands, and replaces the Railway Gun in your inventory, if you do. You can also find the mods necessary to access the weapon, here at Nexus Mods.
In the video below, Youtube user Tyrannicon shows you the Harpoon Gun in action. He points out that the animation shows bubbles around the weapon when fired or while reloading. This suggests that the weapon might have been intended for an underwater segment of some kind. Rad-sharks? Glowing Frog-men? Mer-Deathclaws? We know that Fallout: New Vegas had an underwater segment in it, but there wasn’t really any combat during this time, and there certainly was not a harpoon gun. Well….there was this, but it doesn’t really count, since it didn’t appear in the game without a mod.
Perhaps the weapon was intended to be part of Fallout 4’s upcoming DLC, in which case we might just find out what terrifying creature from the depths this was meant to annihilate. For now, pinning Raider’s heads to the wall with a harpoon will have to suffice.