Vision is a super-advanced AI partially made of Vibranium and is powered by an Infinity Stone (Mind Stone). The Mind Stone was originally portrayed as a containment vessel and a power source for the Scepter. The Infinity Stone granted such diverse abilities to fire energy projectile blasts, manipulate minds, enable teleportation, perform astral projection and allow mental communication.
He has these amazing abilities and can even change his molecular density and yet he's easily defeated by being snuck up on and stabbed in the back.
Note: Wanda's abilities also came from the Mind Stone.
Thus, how was Corvus Glaive able to defeat Vision so easily?