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

Here is Why You Need An Adapter

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

Israel

In Israel, outlets of type C and H are in use.

Type C

Type H

Swaziland

In Swaziland, outlets of type M are in use.

Type M