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

Here is Why You Need An Adapter

The outlet and plug type used in Switzerland are C and J 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

Switzerland

In Switzerland, outlets of type C and J are in use.

Type C

Type J