I get that people really wanted this weapon to transform and are disappointed otherwise. But you all gotta understand that it is the Soul of Cinder, itself, that enables the weapon to transform like it does in its possession. Soul of Cinder is channeling the power of all of those that have linked the fire and as a result, the coiled sword responds appropriately to that particular soul's specialty or essence. But at the end of the day, the coiled sword isn't anything special, itself. It's no different than any other coiled sword you see in the bonfire. In fact, you literally see the Soul of Cinder draws a coiled sword as a makeshift weapon when you first initiate the fight. Its not a "balancing" thing, it's a "it makes literal sense" thing and "lore" thing. The only way it could have all of that stuff in the player's hands is if FROM designed this weapon to specifically scale off of all the bonfires you've kindled in the main game BEFORE obtaining this weapon and to offer a Soul of any of the bosses you've slain that represents STR, DEX, INT and FTH.