Besides the use as a tool, they can also be used as Bone Meal. They are craftable like the vanilla tools with Bone as Steak and Bone Block.
Blacksmith Gavels are a new tool type like Pickaxes or Shovels. Just like Pickaxes they can be used to mine stone-related blocks at a higher speed. Furthermore, they have pretty high attack damage making them a viable weapon, though, at the cost of a lower attack speed.
Due to their enhanced mining technique Gavels have a 30% chance of duplicating mined Ores.
A Gold Ore Block that dropped two Raw Gold when mined with the Gavel.
Besides the use as a normal tool Blacksmith Gavels are also needed to start rituals in the Hephaestus Forge. Every Gavel has a remaining ritual uses counter in their tooltip that shows how many rituals this item can still be used for. More advanced Gavel variants can be used more often.
To start a ritual simply right-click with the Gavel on the Forge after inserting all required items and essences.
Tooltip showing the remaining ritual uses.
It can shoot powerful energy balls, when an energy ball hits a mob it summons a lightning bolt. It is used like a bow but shoots automatically after a while.
To get an Pixie Utrem Jar you have to right-click on an Utrem Jar with a Pixie in your hand, it's the same with Corrupted Pixie to get Corrupted Pixie Utrem Jar. You can also put water or lava in Utrem Jars with a bucket in your hand, allowing you to store lava without taking up space in chests.
You can craft Dragon Scale with a Mystical Dagger and a Dragon Head, you just need to put them in a crafting grid. The Dragon Scale is used in the crafts of Draco Arcanus Tools and Armors.
Seeds can be anbtained by crafting a Yellow Orchid with a Arcane Gold Ingot. Allows you to grow a Golden Orchid which when harvested gives you an Arcane Gold Nugget.
By throwing it, at the time of the burst of the Seed Bullet this one will drop a seed randomly (as for example: a potato, carrot, etc...). To craft a Seed Bullet, you will need an Arcane Crystal Dust and 4 seeds.
Throwing it on an entity will make it teleport away in a 50 blocks radius.
It can be right-clicked up to three times to fully repair all items in your inventory. Combine it in a Smithing Table with an item to apply the Indestructible enchantment (before 1.17) or the Eternal modifier (1.17+). This will consume the Eternal Stella.
Mundabitur Dust can be used to craft Arcane Gold Ingots or to transform various different things.
When drunk it will grant 35 Aureal to the player. It can also be used to input Aureal into the Hephaestus Forge.
The Sanity Meter allows to you to see your current Aureal and Corruption values. To get an exact amount you need to right click it.