The first thing isn't an error message. It's also entirely unrelated to the +11 item. The +11 item restores stamina by 11. It's the only one you'll ever get too.
The message is just the info page for Emergency Defense, which shows when you hit the left button of the two on top of the screen with the "Warning" stuff.
The items are dungeon boosts called Talismans. They are a one-time use item that gets used up automatically when you enter a dungeon with them in your inventory. Bank them for later unless they're time (green text with numbers in it on the bottom of the description)
Teleia - Level 70 Caster
무한의Hope - Level 61 Witch
Account ID: EDream