There are a lot of tools you can equip in your prosthetic arm in Sekiro: Shadows Die Twice, but one of the best is the firecrackers. When used, this item will stun most enemies in front of them, providing you with a brief window to attack. Like other tools, you will need to go hunt for this object and Sekiro doesn’t offer any hints as to where it’s located.
You can find get the firecracker tool by purchasing it from the crow vendor in the Ashina Outskirts. Once you defeat or run by the first general enemy, you’ll enter an open space with various enemy patrols. Try your best not to alert these foes, as there is quite a lot of them and they can quickly overwhelming you. Make your way downhill to the left until you reach the dilapidated building with the old woman in it. Now proceed down the path leading to the gate.
There will be a grapple point on your left right where part of the gate meets the cliffs. Launch up there and then scale your way up the ledges until you reach the top. There will be a tent with several crows hanging around it. The firecracker tool can be bought from the merchant in the tent for 500 coins. After you get the tool, head back to the hub and speak to the man who built your arm. He will outfit it with the firecracker gadget for free.