Who said "A warrior's greatest weapon is not steel, but will."?

This quote is attributed to Grey Worm.

A warrior's greatest weapon is not steel, but will. - Grey Worm

"A warrior's greatest weapon is not steel, but will."

Grey Worm Strength

"I am Grey Worm. I have no name."

"Unsullied do not fear death."

"We are the dragons' soldiers."

"A soldier's duty is to obey."

"Strength comes from within."

"A woman should be proud of who she is."

"A strong woman can overcome anything."

"The only thing I'm good at is killing."