You’ll get the Lightning Staff as a reward for helping the staff maker’s assistant, in Hubble. This is an optional item and it can’t be found or bought anywhere else in the game.

Warning: this guide contains minor spoilers for Dragon Quest VII.

Helping the staff maker assistant

You’ll unlock the town of Hubble when you restore the last Red Pillar. 

Once you’re teleported to the island, head to the eastern edge, past the Rucker Castle, to reach Hubble. Exit the town through the north to get inside the castle. 

This castle has 4 towers. Head to the lower right tower. There are two chests on the first floor with gold and a Cloak of Evasion. You’ll find the staff maker assistant on the second floor. He’ll ask you to help him open a chest.

To open this chest you’ll have to walk through the open doors in this room following a cross pattern. Starting from the statue on the left side, go from west to east, and then from north to south. If you do it correctly you’ll hear a clicking noise.

Open the chest to get a bottle of Sparkling Holy Water. The man will thank you and take it from you.

After the staff maker assistant goes away, just continue doing the main quest as normal. You’ll see him again much later.

Getting the Lightning Staff

The second part of this optional quest comes after you defeat Hybris and finish the Hubble main quest. 

Head to the castle again, and go to the basement of the lower left tower this time. You’ll find the staff maker and his assistant in this room. Talk to the assistant and he’ll thank you with the Lightning Staff.

The Lightning Staff is yours! This item has a rather mediocre attack value, but being able to cast Sizzle with it makes it quite useful to have in your bag.

It’s a good idea to give it to a character with high wisdom but few damaging spells, like the priest or the sage, so you’ll have a decent damaging spell that doesn’t consume the MP you’d normally need for healing.