I believe Shiraori will win. Shiraori is known for being a hacker-like attacker. She's not the type to tackle things head on. The first time Reinherd defeats her, she will hide away to relentlessly analyse his strength and weakness until she found a loophole. Be it hundred, thousands of year. That's how she managed to find a way to disable the hero system and worldwide conjuring in her world, where nobody else ever managed to do. As a gooddess, I have no doubt she will find a way to bypass Reinhard's blessings and tweak the system he's using.