You Do Need power plug adapter while traveling from Liechtenstein to Swaziland.

Here is Why You Need An Adapter

The outlet and plug type used in Swaziland is M and in Liechtenstein are C and J. This is how they look like.

Liechtenstein

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

Type C

Type J

Swaziland

In Swaziland, outlets of type M are in use.

Type M