The user throws in a flask of Holy Water in a downward arc, which deals a small amount of flame damage and knockback if it hits an opponent before it hits the ground. Upon making contact with the ground, the flask will burst, and create a pillar of fire similar to Arcfire. The flask will be thrown at a steeper angle if the move is performed in midair. Simon's Holy Water produces red flame, while Richter's Holy Water produces blue flame; the blue flame from Richter's version is an aura hitbox instead of a flame hitbox, unlike Simon's version. However, it does not have the normal aura effect like Lucario, as its power does not increase when Richter's damage is higher. When Richter uses the move, he will also say "Take this!", unlike Simon, who simply grunts when he uses the move.
If the flask is caught before it hits the ground, it can be picked up as an item and thrown. As it is an item, the user is unable to use the move if he is already holding an item (similar to Young Link and Toon Link's Bombs). If the flask is perfect-shielded, however, the flames will damage the user as if it was reflected.
Holy Water is a recurring sub-weapon in the Castlevania series. As with other sub-weapons, usage of Holy Water requires hearts, which act as ammo; the protagonist can keep throwing Holy Water until they either run out of hearts, die, or collect another sub-weapon. When thrown, it creates a pillar of fire which hits multiple times, so it can be used in conjunction with the whip to deal massive damage while locking the enemy in place.
Because Nintendo of America enforced censorship of religious material during the NES and SNES eras, the item was renamed in North America to Fire Bomb. Simon's Holy Water is colored red much like its appearance from Castlevania to Super Castlevania IV, while Richter's is colored blue like in his playable appearances in Castlevania: Symphony of the Night onwards, as opposed to the green color in Rondo of Blood and Castlevania: Dracula X. However, Richter is often shown utilizing a moving flame as opposed to a stationary one in his home series.
Real holy water is water that has been blessed by a clergy member in a church for spiritual cleansing, baptism, or the warding off of evil.
In Smash, its function is a hybrid of how it appears in Simon and Richter's games. The flame stays in one place like in Castlevania through Super Castlevania IV, but rather than being thrown in an arc, it is thrown directly downward at an angle, similarly to how it is used in Rondo of Blood and Symphony of the Night.