It is unknown where Ja-Yearl was supposed to be located in the game; however, it is possible that he was going to be located in the New Londo Ruins and had to be defeated in order for Ingward to present the player with the Key to the Seal. In addition to this, upon his defeat, the Undead King Set probably would have been made available to the player, either through Domhnall of Zena or some other means. For an unknown reason, Ja-Yearl's model does not don his crown.
- Work from the Dark Souls community has revealed that before Ja-Yearl was removed from the game, the developers had already implemented a slightly modified version of the moveset of Old King Allant from Demon's Souls. As a result, through modifying the game files through third-party programs, it is possible for the player to fight Ja-Yearl in place of a boss encountered normally, such as Gwyn.
- Ja-Yearl wields both a unique curved greatsword, which is unavailable to the player, and a Dark Hand. However, in addition to sharing the voice of Old King Allant, his attacks with the Dark Hand could also steal soul levels.