This blade is likely an homage to the legendary Crimson Blade of Muramasa.
A blade of Katana made by Muramasa in 16th century, in Tokyo National Museum ( Wikimedia Commons ) Despite the bad reputation surrounding the blades Murasama forged, they were undeniably of high quality, and were popular in Japan. Muramasa was the first weapon in the game to be the most powerful. Due to being tied to story progression, the Mortal Blade does not carry over into New Game Plus and must be reacquired. Its best modifier is Legendary. That lasted until its damage and knockback were reduced and the ability to equip more than one pair of Feral Claws was removed, long before the 1.1 update, when Hardmode was introduced. The Blood Butcherer is a Pre-Hardmode sword crafted solely out of Crimtane Bars.It is the Crimson variant of the Light's Bane, and as such can be used as a substitute for forging the Night's Edge.Although it is noticeably more damaging and larger than the Light's Bane, it attacks slower.