In Lords of the Fallen, the only way to upgrade your weapons and armor is by interacting with Blacksmith Gerlinde. Once you have rescued her from the cage, she will be available at the Skyrest Hub and you will be able to upgrade your armor and weapons.
At a later part of the game, you will be able to add runes to your weapons and armor. These runes increase your equipment stats which will help you a bit during the battle with the monsters. But to add these runes, you need to find one of the three tablets.
The first and easiest one to find will be the Cracked Rune Tablet. Once you obtain this tablet, head back to the Skyrest Hub and give it to Gerlinde. After that, you will be able to buy and add runes to your equipment by interacting with the Blacksmith. Below you will find where to find this Cracked Rune Tablet.
Lords Of The Fallen How To Get & Unlock Weapon Runes
To obtain the cracked tablet rune, you need to reach the Fitzroy Gorge location. To reach this location teleport to the Vestige Of The Pale Butcher and from there you need to follow the torches and keep going forward to reach Fitzroy Gorge.
From there keep following the path till you reach a cave with old gates blocking the path. You can cross the gate by using your Umbral Lamp. Inside the cave, you will find a wooden broken bridge as shown in the image above. There use the lamp to switch to the Umbral Realm.
Doing this will create a pathway that you need to cross. Go towards the left side a bit and on the right side wall, you will find a hole as shown in the image above. Get inside the hole and use the ladder to go down, keep going through the hole tunnel and at the end, you will find a glowing item which will be the “Cracked Rune Tablet”. Bring this tablet back to Gerlinde and you will be able to add runes to your equipment.