Dragon Buster

The Dragon Buster is a recurring weapon in the Mana series.

Final Fantasy Adventure / Adventures of Mana
The Dragon Buster can be found in a chest in the Buried Ruins.

Secret of Mana
The Dragon Buster can be forged after winning a Sword's Orb from the Thunder Gigas in Pure Land.

Trials of Mana
A very similarly named sword called Dragonsbane can be found by planting gear seeds in the Magic Pot2D or in PeddaHD. It is a weapon for Duran that can be equipped regardless of its class.