He can be found in the first area of Stonefang Tunnel by continuing straight outside, past the pit of lava to the right and the doorway on the left, and riding the elevator down to his workshop.
He is an eccentric, ill-tempered master blacksmith and the last sane townsman left in Stonefang Tunnel. Ed is able to do advanced weapon crafting and, with the heat generated from the Demon soul of Flamelurker, bless weapons with the spirit of mature Demon Souls. His physique and voice are nearly identical to Blacksmith Boldwin because they are twin brothers. Boldwin is quite strong, but pales in comparison to Ed who is supposedly stronger than some Demons. 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.
While Boldwin has only small patches of scales on his skin, the majority of Ed's body is covered in scales indicating he is much further along in the transformation to a scale-covered Demon. If Ed stays, there is a high probability he will share the same fate as the rest of the Excavators. His obsession to continue working the forge, not even stopping when talking to the player, mirrors the scale miner's single-minded quest for ore.