For reaching certain milestones throughout the game, you will get certain emblems appended to your Guild Card.

Emblem	How to unlock
Abyssal Desire	Get the Deep City Ending.
Armoroad's Finest	Complete the Barter Log, Cargo Manifest and Epic Glossary lists.
Eldest Path	Get the True Ending.
Guild Debut	Complete the first Mission.
Limit Master	Learn every Limit Skill.
Master of the Sea	Defeat all Sea Bosses.
Porcelain Wish	Get the Armoroad Ending.
Quests Complete	Complete all Bistro Quests.
Sea Mediator	Finish the 2nd Stratum.
Starry Visitors	Defeat the 6th Stratum Boss.
Treasure Hunter	Open every Treasure Chest.
Yggdrasil Curator	Complete the Item Compendium list.
Yggdrasil Hunter	Complete the Monstrous Codex list.