Helphen’s Steeple Greatsword in Elden Ring can be obtained by killing a Tibia Mariner boss on the Mountaintops of the Giants.

From Castle Sol's entrance, head to the back of the first zone towards a wooden structure and climb the stairs. As you reach the top, keep moving towards an entrance with three lanterns.

“Storied sword and treasure of Castle Sol that depicts an eclipsed sun drained of color. One of the legendary armaments. In Sol, the sight of an eclipse inspires a dreadful awe, preventing an ...