Terraria (Wiki): Gladius

The Gladius is a shortsword that pierces enemies and stabs four consecutive times.

The Gladius is among the strongest shortswords in the game, outperforming the Platinum Shortsword and Gold Shortsword, which were the Pre-Hardmode top ore-based shortswords. 

In contrast to other shortswords, it stabs three times in quick succession, each time at a slightly different angle. Due to its similar attack style to the Starlight, the Gladius can be considered the Pre-Hardmode version of the latter. A Gladius cannot autoswing. Its attack reaches three tiles in radius. At an optimal distance, the Gladius can pierce two enemies. However, multiple bodies will be damaged should they all line up for the player.

When normally used, the Gladius will not emit light, and attacks do not go through walls. It possesses the slowest velocity, making it less effective against fast-moving enemies or when making long-range attacks.

Combat-wise, the Gladius’ decent damage and speed make it effective against slow-moving enemies. All Flask items will imbue their unique effects since the Gladius is a melee weapon.

The Gladius is best modified with Legendary for overall stats improvement.