You Do Need power plug adapter while traveling from Namibia to Vatican City.

Here is Why You Need An Adapter

The outlet and plug type used in Vatican City are C, F and L and in Namibia are D and M. This is how they look like.

Namibia

In Namibia, outlets of type D and M are in use.

Type D

Type M

Vatican City

In Vatican City, outlets of type C, F and L are in use.

Type C

Type F

Type L