It's crazy to think that Mundus is nothing against Urizen.
We learn in DMC 1 that Mundus is the mightiest and scariest demon Dante and co ever faced, possess a reality warping power, and Urizen just surpassing him by planting those Qlipoth roots in human world, absorbing their bloods. And with that, he's now stronger than Mundus, even without the fruit, let alone the power and strength of reborn Vergil.
We learn in DMC 1 that Mundus is the mightiest and scariest demon Dante and co ever faced, possess a reality warping power, and Urizen just surpassing him by planting those Qlipoth roots in human world, absorbing their bloods. And with that, he's now stronger than Mundus, even without the fruit, let alone the power and strength of reborn Vergil.