Sharking is a hardmode weapon that is dropped from Dinichthys. When swung, it will shoot out a Sharkron. Once the Sharkron hits a surface, it will die as it cannot go through blocks. You can only shoot one Sharkron at a time. This sword is not capable of auto-swing.
The Sharkron that are shot out of this sword are the same exact Sharkron shot out of the tornadoes from the Tempest Staff, and those Sharkron are likely a reference to Sharknadoes.