Well, it's part of his commonly quoted name, Mohammed Zahir Shah, so I am surprised about you and redstar never having heard such a reference to him. Regarding his language background,

Mohammed Zahir's father was born in Dehradun, India descending from a Peshawar based Pashtun family, in other words Pakistani based...

Zahir Shah was sent to be educated in France at the Pasteur Institute and the University of Montpellier.[1] He spoke fluent Persian, and some French, English and Italian.[2]

His preference of the Persian language gave him credibility with the single most important group of the country: the Persian-speaking elite of Kabul.[3]

_{*Lunatic*, n.
One whose delusions are out of fashion.}