This was supposed to be a cosmetic system that includes a variety of Epic skins and two signature Legendary skins for each Advanced Class. Now, it will never come to pass.
After taking another look at the system’s design and listening to player feedback in the recent days of the delayed update, the developers have decided to remove Yoz’s Jar.
As they explain, they didn’t want players to feel that the skins found in Yoz’s Jar were necessary for gameplay, especially if gated by a significant monetary or in-game currency barrier. This appears to be the main reason why they have decided to remove Yoz's Jar and the skins from the Wrath of the Covetous Legion Update.
To reiterate, this cosmetic system was supposed to include a variety of Epic skins and two signature Legendary skins for each Advanced Class.
However, the Epic and Legendary skins aren’t purely cosmetic. They provide a small, 1% and 2% Strength/Dexterity/Intelligence, respectively, attack power increase. Every advantage is critical as players engage in Lost Ark’s challenging activities, like the newly introduced Legion Raids.
While Epic and Legendary skins from Yoz’s Jar would've been available to everyone through Crystals and the player-to-player Market, data and feedback suggested they would fetch very high Gold prices, making it difficult for players to acquire a Legendary skin, much less a matching set, developers explain, thus creating an imbalance in the game.