Terraria (Wiki): Flymeal

The Flymeal is a melee weapon that pierces enemies.

The Flymeal is a broadsword with the rare ability to damage friendly NPCs in the game. It is the easiest and least messy way to kill NPCs. It inflicts the Stinky debuff for 5s, but this effect is purely cosmetic. A Flymeal cannot autoswing. Its attack reaches four tiles in radius. At an optimal distance, the Flymeal can pierce two enemies. However, multiple bodies will be damaged should they all line up for the player.

When normally used, the Flymeal will not emit light, and it makes a Whoopie Cushion sound when it inflicts damage. The Nurse receives double damage from the Flymeal, which completely disregards the town NPCs' defense and most likely negates her capacity for self-healing. The Flymeal can also be used to apply debuffs to NPCs when worn with certain armor sets and accessories.

Although the Platinum Broadsword is one of its possible components, the Flymeal has the same attack speed and less damage and knockback than the former. 

Combat-wise, the Flymeal’s decent damage and speed make it effective against early-game enemies. Players shouldn't upgrade their Platinum Broadsword into a Flymeal if all they want to do is increase their damage. With the aid of this weapon, town NPCs can be moved out of the way so that players can use items like beds and chests. All Flask items will imbue their unique effects since the Flymeal is a melee weapon.

The Flymeal costs 35 silver coins and its ingredients are sold for (68 silver coins (Gold Broadsword)) / (77 silver coins (Platinum Broadsword)).

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