Honed Bolt is one of the Dragon Cult Incantations in Elden Ring that can deal lightning damage by raining down a lightning bolt from the sky. This incantation was bestowed upon Godwyn by Fortissax once he was defeated and befriended.
Honed Bolt incantation in Elden Ring can only be unlocked and purchased once you find a specific prayerbook. Let us help you find it.
Honed Bolt Location in Elden Ring

Honed Bolt can be purchased from either Brother Corhyn or Miriel, Pastor of Vows for 7,000 Runes.
Honed Bolt is not available by default at the merchants mentioned above. You must deliver the Dragon Cult Prayerbook to unlock this incantation.

Dragon Cult Prayerbook can be obtained by killing a lone Leyndell Knight in eastern Liurnia. You can find this knight roaming the area directly south of Artist’s Shack. This area can easily be accessed on foot.

Beware of the Lyendell Knight, as he uses the same sorcery to attack the players. Once defeated, he will drop the Droagon Cult Prayerbook. Take this book to Miriel in the north to purchase the Honed Bolt incantation for 7,000 Runes.
Honed Bolt Stats and Uses in Elden Ring
Honed Bolt incantation in Elden Ring requires 24 Faith and 12 FP to cast. It also requires a good sacred seal in addition to one spell slot.

In terms of DPS, it can significantly outperform Lightning Spear which also falls in the same lightning damage category. The damage done can be further enhanced by enhancing it with Gravel Stone Seal.
Because of its ability to be equipped quickly, it can deal damage before enemies have time to think for a counter. You can then repeatedly cast Honed Bolt to stun the enemy and further increase the DPS.