Water is pretty good!

Not only as elemental weapon but also raw wise! At this point we have either Royal Ludroth or Tetranadon weapons; the first focuses more on the elemental side of things, the second more on the raw. Depending on the weapon class and the monster you are fighting you are going to craft one or another.
Extra note for curious people; Barroth muddy armor takes a boat load of water damage and little raw damage; that means that even slower weapon would prefer having a little bit of water element (Tetranadon's weapon) just to chip away the armor and expose its weak skin.