>>279655461
>>279655470
This is just a case of the author being a bigger weeb than you and simply knowing things you clearly don't. As you saw when Ainz fought Shalltear he is capable of drastically raising his power level with all the items at his disposal.
One of his world items is literally just Yogiri's power as a consumable, except not working passively and automatically. Reinhard absolutely stands no chance against the full power of Nazarick.