The Axe Blade in Mortal Shell 2 is a powerful and highly effective weapon, essentially functioning as dual blades. To obtain it at the start of the game, head to the top floor of the Marrowkeep. Purge the Black Vine there, then teleport to the outskirts of Marmor. From there, make your way to the Path of Absolution, proceed to the Condemner's Stronghold, take the side path to the Forgotten Spire, and you'll find the Axe Blade on a ledge inside the tower.
How to Obtain the Axe Blade at the Start of Mortal Shell 2