Easily the most powerful weapon just ahead of the trident, the fire sword does crazy amounts of damage on top of having its pretty good utility. Games often come down to who has one wins, and unless you get a good combo on them they can two tap you with most armor combos. It should still be powerful but maybe lower the damage a point or two to help get it to the point where it can be countered beyond just hoping that the player using it doesn't have at least 2 braincells.