At a standard reinforcement of +10, which can be done with somber smithing stones, this greatsword boasts nearly 300 physical damage, 191 fire damage, both of which benefit from C Strength, C Dexterity, and B Faith scaling, respectively. This means that the weapon is absolutely something you need to put some levels around before it comes online.
Once you do have the levels in F, STR, and DEX to scale this puppy up, you’ll be glad to know the monstrous amounts of damage will be accompanied by a strong amount of poise damage. Some players have even documented being able to stun lock certain bosses in Elden Ring using this weapon, either through its natural R1 / R2 attacks, or through its ability: Taker’s Flame.
Taker’s Flame is reminiscent of the Drake’s Sword R2 in Dark Souls 1 in that it creates a wall of damage that flies outward in a narrow path. Enemies struck by Taker’s Flame are dealt heavy damage, poise damage, and heal the player for a portion of their HP. This ability causes so much poise damage that you can actually use it and follow up with a heavy / standard attack and stun lock many opponents.
Given the potential for stun locking opponents along with the natural HP sap given to Blasphemous Blade, this weapon is essentially just a PvE monster. At high levels, you can farm through heavy amounts of enemies with natural sustain (Who needs crimson tear flasks?) and destroy boss fights with extreme hits.