Who said "Fear is the weapon of those who have already lost."?

This quote is attributed to Lady Sif.

Fear is the weapon of those who have already lost. - Lady Sif

"Fear is the weapon of those who have already lost."

Lady Sif Fear

"I am a warrior of Asgard, and I will not falter in the face of darkness."

"Strength is not measured by the power of one's blade, but by the resolve of one's heart."

"A true friend stands beside you, not behind you."

"We are forged in battle, but refined through compassion."

"Face your fears with courage."

"You can't live your life in fear."

"Snakes. Why'd it have to be snakes?"

"Fear is just another obstacle to overcome."