Temple Key is a Rank-A Sword made from Copper.
|Fused from 3||Ceremonial Blade|
|Attack Points (AP)||10|
|Defense Points (DP)||4|
|Sell Price (Sword Coins)||3,000|
|Sword Contest Points||180|
In this manga, Kent is delving deep inside a cave and coming across a rather large door. Drawing the Temple Key from his scabbard, he places it in an alcove on the wall, theoretically, to open the door (as per the sword's name). Whether this works or not or what exactly is inside the temple is left unanswered by this manga. Perhaps the answer is hidden inside another page.
*Note: The door seems to be the same found in Cavern of Ancient Ruins.