i wonder, could the red glowing sword symbolize something more than a random weapon.
i mean, what if there'd be a plot point where he gets consumed by his vampiric half's lust for blood (like how soma's consumed by hatred and darkness after the other half of his soul finishes rejoining him if you die to final boss in aos).
even if it was just temporary, with alucard regaining his senses once he's defeated at one point it could work i suppose, and if it's a sotn sequel it'd continue sotn's idea of "hero of previous game is a villain here."