Fire Bars first appeared in Super Mario Bros., and have appeared in numerous Mario games ever since. They are not items, but rather stationary obstacles, rods of fireballs that rotate on a block and typically appear in castle levels. The design of the block of the Fire Bar item is based on their design in contemporary 3D Mario games, while the fire is based on the design of fireballs in Super Mario Bros..
The Fire Bar is a battering item that deals flame damage. It features a unique mechanism somewhat involving ammunition, as the Fire Bar features 5 fireballs on it. When swung, the Fire Bar deals fire damage, alongside moderate knockback and damage, with a forward smash being able to KO opponents at 50% when fully charged. Fireballs closer to the hilt deal more damage than those distant from it.
However, the fireballs on the Fire Bar gradually disappear, with one fireball vanishing after every two times the weapon hits opponents. The weapon cannot go below one fireball, lowering its effective range. Throwing the item does not count towards the loss of fireballs, but it does not reset it.
Of note is that the Fire Bar does not have a hitbox on its hilt, and all hitboxes in the weapon are only on the fireballs. As a result, the weapon cannot harm opponents at point-blank range, and hitting with the fireballs becomes more and more difficult as the fireballs begin to dissipate.
Equipping the Bloom Coach, Sword Man, Crispin Support Spirits will give the player a Fire Bar at a start of a match.