To upgrade weapons in Lords of the Fallen, you first need to find that most classic of Soulslike staples: a blacksmith. Though survivors are few and far between in the demon-ravaged lands of Mournstead, you're lucky enough that a grumpy blacksmith named Gerlinde happened to survive, imprisoned by the Hallowed Sentinels and forced to forge ever-more bells for their corrupted shrine.
If you're just starting out and are struggling with Lords of the Fallen's more unconventional mechanics, like the umbral lamp, some tips might make the difference. Before freeing the blacksmith, you may also want to grab some weapons worth upgrading in advance. Either way, here's how to free Gerlinde the blacksmith in Lords of the Fallen so you can access weapon upgrades.
Lords of the Fallen Gerlinde location
To upgrade weapons you first have to acquire a blacksmith, namely, Gerlinde. This NPC can be found hammering away on her anvil in a prison cell in Pilgrim's Perch. Specifically, she's right after you clear the umbral entity and unlock the elevator shortcut leading back up to the Vestige of Blind Agatha in the Bellroom. This is just before you take the next lift down to the Gentle Gaverus boss fight. You'll hear the sounds of her hammering and complaining below, and upon looking down, you'll spy her cell directly below the wooden walkway.
Drop down to defeat the dogs and the Pureblade enemy to get the cell key—I recommend standing on top of the cell and using ranged attacks to kill the dogs before you try and tackle the warrior. Give Gerlinde the cell key and she'll move to Skyrest Bridge—in the room opposite Stomund—the next time you rest. Speaking to Gerlinde will unlock the option to upgrade both your basic and master weapons for Deralium, and she'll sell a few items of her own, too. This will also begin her quest in which you have to locate rune tablets scattered throughout Mournstead and bring them back to her.