One of the most useful and multi-purpose prosthetics available quite early into Sekiro: Shadows Die Twice, the Loaded Axe will help you defeat shielded enemies and disrupt posture with ease.
The Hirata Estate houses several of Sekiro‘s prosthetic tools, and the Loaded Axe is just one them. Much like the Flame Vent, this one is a bit hidden if you don’t venture off the main road just a bit. Start at the ‘Estate Path’ Sculptor Idol, and work you way down the main path, until you come across a large, locked door. You can get past this door on either side, which will then bring into a long road, with explorable areas on both sides. Keep moving until you see two guard standing outside a door, who you can eavesdrop on. Take them out, or ignore them, and hop up onto the top of the door and look to your right.
You’ll spot two guards standing outside a small hut, which is actually a temple. The torch gives away the location if you’re having trouble spotting it. Work your way to those two guards, and a little eavesdropping will reveal that the small hut there is actually a temple housing an important relic. Tackle the guards in your prefered disposal method, and inside the little hut you’ll see a glowing item. Grab it, and you’ll have the catalyst you need to equip the Loaded Axe onto your prosthetic arm.
That’s all there is to it! Having accomplished all this, head back to the Dilapidated Temple, speak with the Sculptor, and equip the Loaded Axe in any free spot under your Prosthetic Tools. This tool will help with the shielded enemies you will soon encounter throughout Sekiro, and is also useful for dealing some respectable posture damage.