Unseal Equipment can be found in the bottom right corner of the game screen, through [Craft]> [Unseal Equipment].
When reaching Angel Ⅲ, the Unseal Equipment Function will be unlocked.

Unseal Equipment by using the amount of Seal Removing Stones depending on the Equipment Rating, Seal Removing Stones can be acquired from Events.
You can acquire Current Options and increase the Unseal Ratings of equipment when successfully Unsealing Equipment.