These seals will allow the unit to change class based on his/her personality. When used on the avatar, it will allow him/her to change to the class selected as his/her talent during the character creation portion. A base unit that used a heart seal can only change to another base class. Same with an advanced class who can change only to another advanced class.
This allows a character who is married to another character (S Rank support) to change to the class of his/her partner. If the character using the seal is a base class, he/she can change to his/her partner's base class, even if his/ her partner is already an advanced class. In the other hand, an advanced class spouse can only change to his/her partner's advanced class even if the partner is still a base class.
This setup allows characters to change to other Classes that are otherwise not available to them. This is considered as a lateral change or "re-classing" so the level stays the same and the stat changes for the adopted class will be applied.
Similar to partner seals but in a non-romantic way. Partner seals will allow a character to adopt the class of another character he/she has an A+ rank support level with. Each character has very limited number of options to have A+ rank with and they can only have that level on one character. However, this is a one-way affair and there's no special support dialogue when raising the two characters' relationship to A+. The "best buds" doesn't necessarily need to have A+ support to each other. For example, Benny has an A+ rank with Hayato. Hayato in the other hand, can have an A+rank support with Azama, Kaden, or Fuga.
The avatar is a special case since he/she only needs to have an A-rank with characters of the same gender to have an A+ rank equivalent support. This gives the avatar a wider array of choices to re-class and learn more skills. Like most seals, this is also considered as a lateral change or "re-classing" so the level stays the same and the stat changes for the adopted class will be applied.
These are not necessarily seals but can be used to change into a special class, not normally available in the game and are available only through DLC. Here are some examples:
Class | Required Item |
Dread Fighter | Dread Scroll |
Dark Falcon | Ebon Wing |
Ballistician | Sighting Lens (DLC, males only) |
Witch | Witch's Mark (DLC, females only) |
Lodestar | Hero's Brand (DLC, males only) |
Vanguard | Vanguard Brand (DLC, males only) |
Grandmaster | Fell Brand (DLC, males only) |
Great Lord | Exalt's Brand (DLC, females only) |