He is an old blacksmith able to do minor weapon crafting. He also sells low-level equipment and items. His physique and voice are nearly identical to Blacksmith Ed because they are twin brothers. He worked in Stonefang Tunnel as a blacksmith up until the coming of the Deep Fog at which point he fled to the Nexus before the situation deteriorated. Like Ed, he carries a Hand of God (likely a family heirloom), a fist weapon worn by the legendary warrior Big M to slay dragons with his fists.
Also like Ed, he has small patches of scales on his skin indicating the miners of Stonefang were once human, transformed into scale-covered Demons by the colorless fog. There is an empty blacksmith station near the water wheel which powers the elevator by Ed, perhaps this was Boldwin's station before he left for the Nexus. When he was younger, Boldwin also lived near Stonefang and used his strength to clear bearbugs from the mine tunnels.