Ideally, you get a sword as your first weapon. For sub 0:50, it's a necessity. For some reason, your weapon is tied to your spawn position: if you spawn in the 2nd or 4th spot (starting counting from the left), you'll get a sword, while the 1st and 3rd spots give a hammer. You can test this out yourself. I've only tested it on PC, it might not be true on other platforms. This does, however, mean that your chances in level 3 of getting good RNG are higher than we thought, as the best spawn position (4th) is paired with the best weapon (sword). I don't think weapon spawn location is tied to any of that, though.