The liquid sword is a very powerful weapon, requiring 95 Attack to wield. It is a very complex weapon as well. Being very powerful, it is also very expensive. Like items that must be recharged, this one must be recharged but in a different way. You must buy Liquid metal cartridges (Grand Exchange is cheapest) and dump it in the metal bottle. The day of the release, the bottle cost 3,000,000 but after a weeks time it skyrocketed to 46,000,000. The cartridges started at 5,000 but quickly rose to 112,000. You must finish Liquid Metal Foundation before this item is wieldable.