Fire Sword II (also known as Fire Sword 2 in the SNES/PS version) is a Double Tech used by Crono, and Lucca. It's learned once both characters learn Frenzy and Fire II respectively. It is more powerful than Fire Sword.
Strategy[]
Due to the high MP cost of Frenzy and Fire II, it's highly recommended to equip Crono and Lucca with the Golden Stud (Silver Stud works as well), wich will help them to greatly reduce the MP cost. This let the player save Ethers, and use this Tech several times. This strategy can be also applied with Ice Sword II, wich have the same MP cost as Fire Sword II.